LOUISVILLE, Ky. -- A leading Southern Baptist theologian spoke out against psychological counseling aimed at turning young gays straight, saying homosexuality cannot be turned off like a switch.

The Rev. R. Albert Mohler Jr. said Monday that conversion or reparative therapy can't bring about redemptive change.

Mohler is president of Southern Baptist Theological Seminary. He spoke to reporters at the start of a conference entitled "Homosexuality: Compassion, Care and Counsel for Struggling People."

Mohler was unwavering in the belief that marriage is only between a man and a woman.

Mohler believes homosexuals can change by accepting biblical teachings. But he said Christians have sinned against gays by "reducing a massive human struggle to simplistic explanations."

Gay rights advocates denounced the conference. Their protest included a prayer for love, inclusion and respect.