Influential Christian pastor and commentator Rev Al Mohler has condemned the "heresy" of racism and called on modern-day Southern Baptists to confront as well as repent of the racism of their founding fathers.

Reflecting on the Charleston church mass shooting, Mohler, president of the Southern Baptist Theological Seminary in Louisville, Kentucky, has described his horror at the "putrid exegesis" of the Bible that was allowed to justify racism in the past.

He says: "The ideology of racial superiority is one of the saddest and most sordid evidences of the Fall and its horrifying effects. Throughout history, racial ideologies have been driving forces of war, of demagoguery and of dictatorships."

He differentiates between heresy and error, and defines heresy as the more serious of the two, "the denial or corruption of a Christian doctrine that is central to the faith and essential to the Gospel." A heretic is someone who can be considered to have abandoned the faith, he says, such as those who deny the Trinity.

Writing for Baptish Press, he says: "The killing of nine worshippers at Emanuel African Methodist Episcopal Church in Charleston SC is a hideous demonstration of this heresy's deadly power. The young white man charged with the killings has not, as yet, claimed a theological rationale for his acts. Nevertheless, he has been exposed as someone whose worldview was savagely warped by the ideology of racial superiority -- white superiority."

He warns that the ideology of killer Dylann Roof is not limited to a small fringe. Its most fertile soil was tilled in the states of the old Confederacy, particularly among Southern Baptists.

"White superiority was claimed as a belief by both Abraham Lincoln and Jefferson Davis, but it was the Confederacy that made racial superiority a central purpose," he says.

"More humbling still is the fact that many churches, churchmen and theologians gave sanction to that ideology. While this was true throughout the southern churches, Southern Baptists bear a particular responsibility and burden of history."

The Southern Baptist Convention was founded by slaveholders who held to an ideology of racial superiority and who bathed that ideology in "scandalous theological argument".

White superiority was even defended by claiming a "curse of Ham" as the explanation of dark skin. He argues that any strain of racial superiority, especially when bathed in the language of Christian theology, is "deadly dangerous".

The Southern Baptist Convention publicly repented of its roots in the defence of slavery in 1995.

But more is now needed, says Mohler.

"We must seek to confront and remove every strain of racial superiority that remains and seek with all our strength to be the kind of churches of which Jesus would be proud -- churches that will look like the marriage supper of the Lamb."

He admits: "We cannot change the past, but we must learn from it. There is no way to confront the dead with their heresies, but there is no way to avoid the reckoning that we must make, and the repentance that must be our own."