In God's eyes there is no seperation of Church and State. The US Church rules the US, and the US rules the world as the 4th horseman.
And how do you know what's in God's eyes? Did (s)he tell you or did you read his/her mind? Obviously, God has no problem with the First Amendment since people of all beliefs and no beliefs are welcome to live in the U.S. and worship or not worship in the way they believe is right.
There is also no U.S. Church. The various Christian sects disagree with each other on many things. Try to tell a Continuationist that glossolalia is wrong or tell a Cessationists that it is right and you'll have an argument at the very least. Some churches believe that baptism must be by immersion for older children and adults while others believe that infants may be sprinkled. Thomas Paine had it right in part 2 of his Age of Reason:
It has often been said that any thing may be proved from the Bible; but before any thing can be admitted as proved by Bible, the Bible itself must be proved to be true; for if the Bible be not true, or the truth of it be doubtful, it ceases to have authority, and cannot be admitted as proof of any thing.
It has been the practice of all Christian commentators on the Bible, and of all Christian priests and preachers, to impose the Bible on the world as a mass of truth, and as the word of God; they have disputed and wrangled, and have anathematized each other about the supposeable meaning of particular parts and passages therein; one has said and insisted that such a passage meant such a thing, another that it meant directly the contrary, and a third, that it meant neither one nor the other, but something different from both; and this they have called understanding the Bible.
It has happened, that all the answers that I have seen to the former part of 'The Age of Reason' have been written by priests: and these pious men, like their predecessors, contend and wrangle, and understand the Bible; each understands it differently, but each understands it best; and they have agreed in nothing but in telling their readers that Thomas Paine understands it not.
Now instead of wasting their time, and heating themselves in fractious disputations about doctrinal points drawn from the Bible, these men ought to know, and if they do not it is civility to inform them, that the first thing to be understood is, whether there is sufficient authority for believing the Bible to be the word of God, or whether there is not?
"It is always to be taken for granted, that those who oppose an equality of rights never mean the exclusion should take place on themselves." -- Thomas Paine: Dissertations on First Principles of Government (July 7, 1795)