Almost half of Catholics who are now unaffiliated 48% left Catholicism before reaching age 18, as did one-third who are now Protestant. Among both groups, an additional three-in-ten left the Catholic Church as young adults between ages 18 and 23. Only one-fifth who are now unaffiliated 21% and one-third who are now Protestant 34% departed after turning age 24. Among those who left the Catholic Church as minors, most say it was their own decision rather than their parents’ decision.
via Leaving Catholicism: Faith in Flux – Pew Forum on Religion & Public Life.
