So recently there was a Twitter video of White Horse Inn where they felt compelled to say that MLK had an "important impact for the gospel":
It seems that Christian ministers and theologians in the Anglophone world generally feel compelled to praise or commend Martin Luther King even though he had literally denied the resurrection and the divinity of Christ. They also feel particularly compelled to affirm, almost creedally, all the standard tenets of Anglo-American civic morality, especially that of civil rights, thus the necessary commemoration of MLK despite him being literally not a believer in even the Apostle's Creed.
I think here Nietzsche may provide an interesting explanation as to why the Anglo-American Christian feels this need to constantly re-affirm the civic morality of the US, and why the American civic morality takes precedence even over theology. The sum of his explanation is: the Anglo had long go decided to substitute God for morality:
They are rid of the Christian God and now believe all the more firmly that they must cling to Christian morality. That is an English consistency; we do not wish to hold it against little moralistic females à la Eliot. In England one must rehabilitate oneself after every little emancipation from theology by showing in a veritably awe-inspiring manner what a moral fanatic one is. That is the penance they pay there.
We others hold otherwise. When one gives up the Christian faith, one pulls the right to Christian morality out from under one's feet. This morality is by no means self-evident: this point has to be exhibited again and again, despite the English flatheads. Christianity is a system, a whole view of things thought out together. By breaking one main concept out of it, the faith in God, one breaks the whole: nothing necessary remains in one's hands. Christianity presupposes that man does not know, cannot know, what is good for him, what evil: he believes in God, who alone knows it. Christian morality is a command; its origin is transcendent; it is beyond all criticism, all right to criticism; it has truth only if God is the truth--it stands and falls with faith in God.
When the English actually believe that they know "intuitively" what is good and evil, when they therefore suppose that they no longer require Christianity as the guarantee of morality, we merely witness the effects of the dominion of the Christian value judgment and an expression of the strength and depth of this dominion: such that the origin of English morality has been forgotten, such that the very conditional character of its right to existence is no longer felt. For the English, morality is not yet a problem.
-Twilight of the Idols
The Americans have long ago gotten rid of God from the public and civic sphere. Thus, the civic morality of the land is more important, and more "self-evident", than theological truth claims. So if the Christian pastor in America is to access the public space to speak about his faith, he must "pay his penance", and that penance is fanatically re-affirm the civic morality of the age. If I may adapt Nietszche's point for the US:
They are rid of the Christian God in the public space and now believe all the more firmly that they must cling to civil rights morality. This is an Anglo-American consistency; we do not wish to hold it against little moralistic David Frenches. In America one must rehabilitate oneself after every little attempt to whisper the name of Christ in public by showing in a veritably awe-inspiring manner what a civil rights fanatic one is. That is the penance they pay there for daring to even peep their religion in public.
Thus, the constant need to reaffirm the civic morals of the US is because they have replaced God as the foundation of the polity with morality instead, you have to declare your allegiance to such morality before being granted an audience to the public. In short, it has become a secular god as it were to whom they must pay the toll before they are allowed to speak. Denial of the creeds of this secular religion means banishment from all respectable company and an audience with the American People with capital P.
If American Christians, and not just American Christians but all Christians, want to preach the full lordship and supremacy of Christ over all, they need to overcome this instinctive visceral moral conviction that their civil rights claims are "self-evident" or obvious, or that it is prior to theological truth claims. Only then will they be empowered to speak boldly of the Gospel without offering sacrifices and haiographies to the civil rights religion.