You've not fought against it very well, have you?

• You have school "voucher" schemes for religious schools, which do shit like teach kids that Evolution is wrong because of the bible.
• You added "In God we Trust" do your money and added "Under God" to the pledge of allegiance in the 1950s (The pledge, with or without it, is in itself a form of state worship).
• You have had presidents (Reagan, Bush II) openly promote the idea that America is a Christian state through historical falsehoods.
• One of the most powerful factions in your government are American Evangelicals who have used their power to promote religious based laws, especially against women and minorities.
• Every President in recent times has had to show themselves to be openly Christian, with "not being christian (enough)" being a common attack strategy.

And that's just Christianity, if I was going to go into how you worship the state...

• You have Four Faces of Presidents carved on a literal sacred mountain.
• You make your kids pledge allegiance to the state every morning (I pledge allegiance to the Flag of the United States of America, and to the Republic for which it stands).
• You have two (2) congress funded art pieces that depict George Washington as a God (Washington Enthroned and The Apotheosis of Washington), the latter of which is in the oculus of the Rotunda at Congress for everyone to see.
• The Lincoln Memorial is straight up designed like a Greco-Roman Temple.
• You have, as a social norm, displaying your flag outside your house.

How is that not going to be interpreted as "religious"?

Now, I know someone is going to be all "lol aren't you from the uk where you worship the royal family" well guess fucking what:

1. Barely anyone in the UK worships the royals, especially where I'm from (Scotland) and the people who do even in England are considered weird. Our relationship with the Royals as a country is usually one of aggressive irreverence. My family's nicknames for the king includes "The Jug Eared Dwarf", "Chuckie III" and "Tearlach an Chluas".
2. Despite having two (2) established churches (Church of England and Church of Scotland), non religious people make up the majority and the UK is aggressively secular.
3. Despite the established religion and having the (in practice) head of state also be the (in practice) head of the Church, none of our politicians try and use religion to justify their bullshit and those who do are considered wankers.

America, in the eyes of most of the world, is aggressively religious, not just in terms of christianity but also in worship of the state.