I suggest it stems from a real and visceral hatred of Christianity on the part of a far left from whose Marxist roots sprang the insanity of political correctness in the first place. Insofar that Christianity is based on truth, and I mean absolute truth, it cannot be tolerated by the tyranny of political correctness which is based on the fog and human debasement of moral relativity. For the Christian, Jesus, who is truth, instructs in His absolute truth. This is seen by those in the world who have been indoctrinated by political correctness as being in direct conflict with their acceptance of moral relativity. Moral relativists must insist there is no absolute truth in order to maintain an unburdened conscious while pursuing their fallen life style. So who does the world condemn? Themselves, who fallen, live outside God's word or those whose very lives are to serve as testament to the infallible and eternally truthful Jesus Christ? Insofar that the world does not want to be reminded of its inequity, it must condemn Christianity as intolerant or noninclusive.
The State also has a vested interest in the abolition of Christianity and has faithfully been fulfilling its role since the encroachment of Marxism on the American political system starting immediately after WWII. Since then, America has been increasingly moving towards a Marxist state which is presently highlighted by the extremism of the Obama administration and its plethora of policies designed to run the lives of its subjects, not for freedom, but for "the greater good." In the Marxist state, which is quite naturally run by the fallen, the "greater good" always includes the most good for themselves. Hence, they cannot tolerate subjects whose allegiance is to a higher authority. Particularly, a righteous and truthful higher authority who desires a fruitful and joyous life for all His creation. The Marxist state demands total and complete subjugation of its population to the state while Christians rightfully put their faith in the Lord and not in man or his institutions. Therefore, Christianity cannot exist in the Marxist state.
So, attacks on Christianity will continue in all forms as the natural reaction of the fallen nature of man. Insofar that man and his institutions are incapable of correcting his own natural, fallen state, the only salvation for mankind is Salvation itself.