Young Sheldon's Series Finale Reveals Why Mary Was So Religious In Big Bang Theory
The "Young Sheldon" finale ties up a lot of loose ends between "The Big Bang Theory" and the prequel sitcom. For example, viewers finally get to see George's (Lance Barber) death (which had been planned out since Season 1), while Sheldon (Iain Armitage) finds a new home in California. It's also explained why Mary (Laurie Metcalf) is so different on "The Big Bang Theory." On "Young Sheldon," Mary (Zoe Perry) turns to religion as a source of comfort after George dies.
At first, Mary just attends church services more frequently, but the longer she struggles with her grief, the more she leans into her faith. Then, over their last family dinner, Mary makes it clear that she believes Sheldon and Missy's (Raegan Revord) souls won't be safe unless they get baptized. She begs them to go through with it, and Sheldon agrees (despite his atheist beliefs), donning full scuba gear to the ceremony. However, Missy walks out since she's too distraught over her dad's death.
Although these scenes bring some humor to an otherwise emotional episode, they also serve to retroactively explain why Mary is even more conservative on "The Big Bang Theory" than she is on "Young Sheldon." Up until the finale, Mary is never too judgemental or overbearing in forcing her religious beliefs on others. George's tragic death in Season 7, Episode 12, changes everything.
Mary wasn't always religious
As "Young Sheldon" fans know, Mary wasn't always a religious woman. Her mom Connie (Annie Potts) certainly isn't, so her devotion to the Lord did not come from her upbringing. Mary was a typical wild teenager who drank, smoked, and had sex before marriage. She even got pregnant with Georgie (Montana Jordan) before she married George. It was only after the birth of Sheldon and Missy that she turned to the church.
It is revealed in Season 2, Episode 14 — "David, Goliath, and a Yoo-hoo from the Back," that Mary had a difficult pregnancy with the twins and her doctor was worried Missy wouldn't survive. Mary hoped and prayed that her daughter would be okay and, in return, vowed to live the rest of her life devoted to Christianity and its ideals.
From that moment on, Mary honors her pledge. Throughout "Young Sheldon," the Coopers regularly attend church and Mary eventually gets a job there "doing the Lord's work." Although she briefly leaves the church after Georgie and Mandy (Emily Osment) have a child out of wedlock, she returns in Season 7. But her faith gets much stronger later in life and viewers now know this is because of George's death. Mary takes comfort in knowing that his soul is safe up in heaven and that he's looking down on her.