Simplify the following text for a Grade 10 native English-speaking person.
Original: Cameron was once an atheist , but when Kirk was 17 , during the height of his career on Growing Pains , he developed a belief in God , and became a born-again Christian .
Simplified: Cameron was once an atheist , but around the age of 17 - 18 , during the height of his career on Growing Pains , he developed a belief in God , and became a Christian .