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Clergy Team

Rabbi Richard Rheins, Senior Rabbi

Born in Cincinnati, OH, Rabbi Rick Rheins spent most of his youth in Indianapolis, IN. He earned a BA from Indiana University in 1980, a Masters degree from Hebrew Union College-Jewish Institute of Religion in 1988, and was ordained a Rabbi from HUC-JIR in 1989.  From 1989 to 1995, Rabbi Rheins served as Associate Rabbi at Temple Beth El in Chappaqua, NY, with Rabbi Chaim Stern z”l, the acclaimed liturgist.  In 1992, Rick was selected by the Central Conference of American Rabbis to serve on the Responsa Committee (at the time, the youngest ever to be so selected). He has authored a number of halakhic responsa as well as other scholarly articles.

In 1995, Rabbi Rheins was named by Temple David of Monroeville, PA, a suburb of Pittsburgh, to succeed its founding Rabbi of 35 years. In the ten years that Rick led Temple David, it grew substantially both in its membership and in the number of programs and services. During his tenure, he received many community honors, served on the boards of several organizations, and was especially active in communal interfaith efforts.

In July 2005, Temple Sinai selected Rabbi Rheins to succeed its founder, Rabbi Raymond Zwerin.   Rick’s scholarship, passion, commitment, and devotion to God and the Jewish people are evident in the number and diversity of new services, classes, and programs at Temple Sinai. Rick is an enthusiastic and acclaimed teacher and he strives to create opportunities of engagement for every member.  In addition to serving Temple Sinai as its Senior Rabbi, Rick is the immediate Past-President of the Rocky Mountain Rabbinical Council and is the Vice-President of the Solomon Freehof Institute of Progressive Halakhah.  He also serves on the National Council of AIPAC as well as other local boards, including the ADL.

Rabbi Rheins is married to Rabbi Susan Miller Rheins.  They are blessed with three children, Joshua, Samuel and Jakob.

To contact Rabbi Rick Rheins, please call 303.759.1827 x307 or send him an email.

Rabbi Jordy Callman, Assistant Rabbi

Originally from the Boston area, Rabbi Callman was raised in a family active in their congregational community. Attending NFTY EIE’s semester in Israel (now URJ Heller High) and Hebrew College’s Prozdor High School program as a teen, Rabbi Callman developed a deep a sense of comfort and belonging in Jewish spaces. She earned a B.A. from the University of Pittsburgh in 2014 and was ordained a Rabbi from Hebrew Union College - Jewish Institute of Religion in Cincinnati in 2019.

As a Jewish Foundation Fellow, Rabbi has brought her warmth, knowledge, and expertise to the Rockwern Academy, Xavier University’s Brueggeman Center for Dialogue, Rockdale Temple in Cincinnati, Ohio, and the Jewish Federation of Cincinnati. From 2015-2016 Rabbi Callman served as Student Rabbi at Temple Beth Sholom in Marquette, Michigan, and from 2016-2017, she served as Student Rabbi at Temple Beth El in Flint, Michigan. Rabbi Callman also served as the rabbinic intern at Congregation Beth Tikvah in Columbus, Ohio. As a program director at Mitzvah Corps, Rabbi Callman led summer programs in Seattle, Israel, New Orleans, and Costa Rica. Rabbi Callman’s commitment to Israel shines through in her congregational work as well as the many Israel programs and trips she has led.

In March 2019, Temple Sinai selected Rabbi Callman to serve as Assistant Rabbi. Rabbi Callman’s love for learning and building Jewish community make her an inspired selection to join the warm community of Temple Sinai. Rabbi Callman has a unique passion for food and cooking, having written her rabbinic thesis on American Jewish food and identity. Rabbi Callman and her husband Matthew are thrilled to be part of the Temple Sinai and Denver Jewish community.

To contact Rabbi Jordy Callman, please call 303.759.1827 x306 or send her an email.

Dan Yolles, Cantorial Soloist

Dan Yolles has been a part of the Temple Sinai community since he attended preschool many years ago and has been serving this community over the past several years, musically, spiritually and in the preschool. He graduated from CU Denver with a bachelor’s in Human Development and Family Relations, studied music education at CSU and has over 10 years of experience teaching music in a variety of settings. His passion for education, music, Judaism, Israel, and mentorship drives him to make the biggest impact he can on our community and keeps him up to date with the latest trends in music education and important Jewish topics. Dan is also a professional musician who has been lucky enough to be able to share his music around the world. He and his fiancé, Ali Weiss have 2 lovely dogs and enjoy spending time outside in their free time.

To contact Dan Yolles, please call 303.759.1827 x311 or send him an email.

Rabbi Raymond Zwerin, Rabbi Emeritus

Rabbi Raymond Zwerin was ordained as a Rabbi from the Hebrew Union College-Jewish Institute of Religion in Cincinnati, OH in 1964. In 1989 he received a Doctor of Divinity degree from HUC-JIR. He is the founding Rabbi of Temple Sinai, and has been serving in the Denver community since 1964.

Rabbi Zwerin was co-founder and president of A.R.E. Publishing, Inc., a major producer of creative Jewish educational materials for children and adults. He is a past Executive Board member of the Central Conference of American Rabbis, and past president of the Midwest Association of Reform Rabbis, and the Rocky Mountain Rabbinic Council.  Rabbi Zwerin is a founder of Theodor Herzl Jewish Day School of Denver and a founder of Babi Yar Park Memorial to the Holocaust and was active in the cause of Soviet Jewry.

He is the author of over a dozen books for children and teachers and the editor of some 700 titles. One of his latest books contains 98 of his High Holy Day sermons and is entitled, "Forty Years of Wondering". His most recent publication is also his first novel, "Holy Fire", a biblical mystery intertwined with a Holocaust story of redemption.

Together with his wife Rikki, Rabbi Zwerin has two married children, Ron (Julie) and Dina (Darren) and four grandchildren, Noah Asher Boivin, Elizabeth Rose Zwerin, Ethan Reuben Boivin and Bradley Ryan Zwerin. He is an avid Colorado Rockies fan and can be seen at the ball games with several people surrounding him listening to his commentary on the game.



Greg Kellner

Executive Director


Greg has been working in the Jewish nonprofit world for more than 20 years. Before joining the Temple Sinai team, Greg served as the Founding Director of URJ 6 Points Sci-Tech Academy, Senior Assistant Director of the URJ Crane Lake Camp and as the Assistant Director of the URJ Eisner Camp. Greg spent the summer of 2007 at Wilshire Boulevard Temple Camps in Malibu, California overseeing the music program and five years as the Youth Advisor for Temple Sinai in Washington, D.C. He is an alumnus of the Yitro Leadership Program, a professional development program for assistant camp directors through the Foundation for Jewish Camp.

Prior to his time at camp, Greg worked as the Manager of Finance and Administration for the Digital Media Association (DiMA), a DC-based trade group dedicated to promoting awareness of new digital music and video technologies. While in Washington, Greg also served as a soundboard engineer for the NHL and MLB on XM Satellite Radio. Most notably, his passion for Judaism, technology and music met when he produced XM’s “Radio Hanukkah,” the first national radio station dedicated to Jewish music.

Greg holds an MPA from CUNY Baruch College in Manhattan and a BA in music technology and broadcast communications from American University.

Greg enjoys playing the guitar, loves cooking outdoors and being in front of the grill. As an avid skier, Greg travels the world, looking for snow adventures!

To contact Greg Kellner, please call 303.759.1827 x309 or email

Lisa Thorner

Associate Executive Director


Lisa Thorner joined the Temple Sinai staff in January of 2009 as the Director of Programming and Volunteer Recruitment. In addition to planning and implementing programs, Lisa is responsible for encouraging volunteer participation. Lisa has extensive experience in event planning and brings an abundance of energy to Temple Sinai.

Prior to Temple Sinai, Lisa spent 17 years working in college athletics. She worked at the Western Athletic Conference from 1997-2007 where she served as the Assistant Commissioner for Championships and the Senior Woman Administra­tor. While at the WAC, Lisa was responsible for planning championships for 17 different sports. Prior to the WAC, she spent five years as the Assistant Director of Media Relations at San Diego State University.

Lisa loves to interact and work with people and has a vast experience in event planning and development. She has planned events, both large and small and helped plan annual fundraisers for The Gathering Place and

Lisa graduated for the University of Colorado, Boulder with a degree in Journalism. Lisa is a Denver native and is the proud mother of two boys, Josh and Zach.

To contact Lisa Thorner, please call 303.759.1827 x315 or email



Lauren Bubis

Administrative Assistant


Lauren Bubis began working at Temple Sinai in January 2018. She graduated in 2008 from the University of Wisconsin-Madison with a degree in Political Science and Jewish Studies. She worked with the programming, membership, and development departments at Temple Sholom of Chicago from 2008 to 2011. Lauren then moved to Houston for three years where she was the Special Events Coordinator at Jewish Family Service. For a year, she served as the Community Engagement Associate at the Jewish Federation of Nashville and Middle Tennessee. After a year in Nashville, she moved to Orlando where she worked as an Accessibility Consultant for the University of Central Florida. In June 2017, she arrived in Denver with her husband, David and daughter, Sadie. Lauren and her family love Denver and have begun to plant roots in the Mile High City!

To contact Lauren Bubis, please call 303.759.1827 x322 or email



Melissa Maahs

Staff Accountant


Melissa Maahs joined the Temple Sinai staff in January of 2018 as Staff Accountant. She has been in Colorado since 1991 and enjoys gardening, cooking and spending time with her two grandsons as well as her dogs and cats. Melissa is your contact for paying your account with Temple Sinai.

To contact Melissa Maahs, please call 303.759.1827 x314 or email


Yoni Buckman

Program Specialist


Yoni Buckman has been working in Jewish organizations since 2014. Yoni began his work in Jewish congregations as the Youth & Family Educator at Adas Israel Congregation in Washington, DC. While living in the DC Metro Area, Yoni built a community of young Jewish professionals as a founding member of the Bethesda Moishe House.

Yoni moved to Denver in 2017 and has worked as the Director of Communication & Engagement at BMH-BJ and as the Colorado Design Strategist at UpStart. Since moving to Denver, he has also volunteered in the Colorado Jewish community, serving as a YAD Ambassador and sitting on the board of B’nai B’rith Colorado as their Marketing Chair.

Yoni lives with his dog, Stevie, and enjoys cooking, hosting Shabbat dinners, and visiting family across the country and in Israel. He is thrilled to join Temple Sinai’s enthusiastic staff and warm community.

To contact Yoni Buckman, please call 303.759.1827 x312 or email


Education & Youth


Ron Leff

Director of Education


Ron Leff has been involved in the field of Jewish education for over 25 years. He holds a MA in education from the American Jewish University (formerly University of Judaism) in Los Angeles and a BA in Psychology from Wayne State University in Detroit. Ron was granted the title of RJE (Reform Jewish Educator) by the Reform Movement in 2000.

Ron began his work in Jewish education as a Religious School teacher, Youth Group Advisor, Youth Director and camp counselor. From 1999 – 2016, Ron served as the Director of Religious Education at Temple Emanuel in Denver and at Adat Shalom Synagogue in Farmington Hills, Michigan, prior to that. He also worked as the Supervisor of Jewish Programming for Tamarack Camps in Michigan. He has been an active member of the Jewish Educators Council and served on the Board of the Association of Reform Jewish Educators.

Ron and his family live in Aurora. He is excited to join the Temple Sinai staff and work with the clergy and board in providing engaging educational programs for our congregation.

To contact Ron Leff, please call 303.759.1827 x308 or email



Sheila Purdin

Preschool Director


Sheila Purdin began her career in early education twenty eight years ago in her native Seattle. She is on the board of Early Childhood Educators of Reform Judaism, serving as VP of Marketing. During her twenty years in the Atlanta area, she was director of two Reform preschools, actively participated in the Jewish Early Childhood Council of Atlanta as both Chairperson and Conference Coordinator. She previously sat on the PJ Library of Atlanta board and participated in the URJ Pursuing Excellence in Your Early Childhood Center Community of Practice. Sheila is thrilled to be a part of the Temple Sinai Preschool and greater synagogue community. She lives with her dog, Lulu, and has two adult children who are pretty fantastic.

To contact Sheila Purdin, please call 303.759-0755 or email



Julie Spitz

Assistant Preschool Director



Julie Spitz has over 25 years of early childhood education experience as a teacher and administrator. She has also served as an Accounts and Office Manager in a medical setting, working in close partnership with families, building professional community relationships. Julie is currently the Lead Teacher of Room 105, and will assume the Assistant Director position in a fulltime capacity after Winter Break on Tuesday, January 7.

To contact Julie Spitz, please call 303.759.0755 or email

Wed, October 28 2020 10 Cheshvan 5781