Tim Farron was challenged on his position during an interview with GQ Magazine.
It's not the first time he's been asked about his Christian faith and beliefs about same-sex relationships.
In an interview with the BBC after his election as leader in July 2015 he refused to answer the question three times.
Asked by GQ Magazine whether he believed homosexual acts to be sinful he replied: "I'm not a religious leader; I'm a political leader. I think that everybody is utterly equal.
"People should be free to love who they want and marry who they want.
"But I don't go making theological pronouncements. One of the reasons I joined the Liberals was because of lesbian and gay rights.
"Friends of mine were gay and I saw how they were treated and bullied.
"I want a society where people are valued for who they are."
The MP for Westmorland and Lonsdale has spoken openly about his Christian faith in the past.
