A group of pastors is suing the state of Illinois over a law that bars therapists and counselors from trying to change a minor’s sexual orientation, saying the prohibition violates free speech and religious rights.

The federal lawsuit seeks to exclude clergy from the ban that took effect Jan. 1, arguing that homosexuality is “contrary to God’s purpose” and a disorder that “can be resisted or overcome by those who seek to be faithful to God and His Word.”

Illinois is among five states with bans on so-called gay conversion therapy for youth under 18, a practice critics have called psychologically damaging.

State Rep. Kelly Cassidy, a Chicago Democrat who sponsored the law, said people she’s met with who have gone through conversion therapy told of feeling suicidal, humiliated and alienated from their families. “This is torture, this is abuse. We can’t sanction that,” she said.

President Barack Obama expressed support for such laws last year.