In an all-Christian edition of Q&A, Australian Christian Lobby leader Lyle Shelton was confronted over a visiting American ally accused of equating gay rights with the rise of the Nazis in a panel debate that traversed everything from indigenous disadvantage to terrorism.

Mr Shelton, appearing on the program's panel for the second time in eight weeks, was confronted by an audience questioner over his support for visiting Christian author and broadcaster Eric Metaxas and the American's apparent comparison of gay advancement with the failure of churches to oppose the rise of the Nazis. "Do you think these comments are acceptable in a tolerant society such as ours, and are similar comments what we have to look forward to in an upcoming plebiscite debate on same-sex marriage?" audience member Daniel Comensoli asked.

Mr Shelton said Metaxas, the ACL's guest for its national conference, had been taken out of context. But he added that in modern debates, he agreed with the American "in terms of the church being silent about certain cultural trends and going along with things which are contrary to the teachings of the church, whether it's on marriage or something like that".

"That's the context with which Eric was making that point and I think it's a good point because I'm very concerned that the church isn't speaking up enough on this issue, because it's a big social justice issue, it's a big public policy issue and it has implications for the future of society, freedom of speech, freedom of conscience and particularly for the freedom of children to be allowed wherever possible to know their mother and father and this is the sort of public policy that will change that."

Australian Christian Lobby leader Lyle Shelton on Q&A. Credit:ABC's Q&A

Of Metaxas, whose final Australian appearance on his "Fearless" tour is at Scots Church in Melbourne on Wednesday April 27, Mr Sheldon said: "There's not an anti-gay bone in his body. He's not anti anyone. He's a lovely man but he believes marriage is between a man and a woman."

Fellow panellist Julie McCrossin​ rebuked Mr Shelton in response: "I do feel it's introducing to the Australian conversation an intensity and a savagery that is not normally part of our pluralistic society. As we move forward towards this question of whether we have equality under the Marriage Act or not, we don't want to descend into this kind of brutality."