Melissa Joan Hart on Her Faith-Based Movie Role, Turning 40

— -- Melissa Joan Hart played a sarcastic and funny adolescent on “Clarissa Explains It All” and then a teen with magical powers on “Sabrina the Teenage Witch.”

Now the mother of three is taking on a more serious role in the faith-based film “God’s Not Dead 2.”

In the film, Hart, 39, plays a high school history teacher under fire for answering a student's question about Jesus.

Hart described the role as “challenging” in an interview with ABC News’ Paula Faris that aired today on “Good Morning America.”

“In this case, she's an introvert ... a woman who stands by her faith,” Hart said of her character. “She wasn't raised with a faith and so she comes to her own beliefs and grows her own faith and then she has to stand by that conviction and kind of unwavering.”

With the movie’s focus on faith and the separation of church and state, Hart said there is an important message of tolerance.

“There shouldn't be one religion represented in anything, but at the same time we need to be tolerant to all religions,” Hart said. “I think it's just really about tolerance all across the board for everyone.”

Off-screen, Hart is raising her three sons and preparing for an important milestone. The actress will turn 40 later this month.

“I think the opportunity to watch my kids get older and really be a part of their life,” Hart said what excites her about entering her 40s. “Just finding new adventures and watching them grow and change and mold and seeing the little men they become.”

"God's Not Dead 2" is in theaters now.