Due to gerrymandering, even if republicans receive 68% of the seats, it doesn't mean 68% of the votes went to them. They might very well be able to take 68% of the seats with under 40% of the votes.
According to an average of all 2023 Gallup polling, about three in four Americans said they identify with a specific religious faith. By far the largest proportion, 68%, identify with a Christian religion, including 33% who are Protestant, 22% Catholic and 13% who identify with another Christian religion or simply as a "Christian."
A large number of Trump supporters are evangelical Christians.