Donald Trump must "repent of sin" and turn to faith in Christ, the head of the Southern Baptist Convention's (SBC) Ethics and Religious Liberty Commission has said.

In an interview with CBN, Russell Moore said his "primary prayer for Donald Trump is that he would first of all repent of sin and come to faith in Jesus Christ".

"That's my prayer for any lost person," Moore added.

It's not the first time the SBC leader has spoken publicly about Trump. The two recently rowed following comments from Moore that the Republican presidential candidate – as well as his likely opponent Hillary Clinton – represented "an amoral sort of vision of America that isn't what we believe in".

"What we have in the Donald Trump phenomenon as well as in the Hillary Clinton phenomenon is an embrace of the very kind of moral and cultural decadence that conservatives have been saying for a long time is the problem," Moore said.

He criticised "conservatives who were saying in the previous Clinton era that character matters, and rightly so, who now are not willing to say anything when we have this sort of reality television moral sewage coming through all over our culture".

Trump subsequently hit back at Moore, branding him "a nasty guy with no heart" and "a terrible representative of Evangelicals".

In his latest comments, Moore said he hoped a conversion to Christianity by Trump would mean a change in his policies.

"And then [my prayer would be] that he would be somebody who would act in terms of principles of justice, which would mean a change, not only in terms of the way in which he's changing the moral character of people, including the people that are supporting him and getting on the bandwagon, having had to excuse things that they've never had to excuse before and then of course in terms of being a ruler in a limited sense within an American constitutional framework who understands principles of justice. That would be a remarkable change," Moore said.

Trump has been widely criticised for his aggressive rhetoric, especially his hard line on immigration. He has pledged to build a wall to slow down the number of Mexicans entering the United States, and in July last year claimed that Mexican immigrants were responsible for a significant number of rapes in America. He has also called for a ban on all Muslim immigrants; a line that was later used by Somali terrorist group al-Shabaab to suggest that America discriminated against its Islamic population.

However, Trump does already identify as a Christian, and has proved popular with the white evangelical voting bloc, although he's polarised opinion among evangelical leaders.

He has a number of high profile supporters such as Robert Jeffress, pastor of First Baptist Church, and President of Liberty University Jerry Falwell Jr. But he has received fierce criticism from others, including Moore.

Trump was baptised into the Presbyterian Church as a child, and has promised to protect Christians if he takes office later this year.