America gives you the freedom to be a hermit in the mountains, a high-rollin' city banker, a hard-hitting investigative journalist, a farmer, a factory worker etc etc. you can be any religion you want in the US, you can legally decide not to have any religion.
There are a lot of social pressures as you rightly mentioned but you can, if you want, completely shun them and be prepared to deal with the consequences.
Because that's the issue, isn't it? Having the freedom to legally do something does not protect you from the inevitable consequences. You can paint your house red and paint a giant yellow hammer-and-sickle on it if you want but you should be prepared for the abuse you receive afterwards. You can legally go and insult a football team to their face but you must be ready for the beating you get as a consequence. You can decide to be an open atheist in a bible-belt hick-town but you should be prepared for the social ostracisation.
To dial a cliche here; Freedom isn't free, even in a world of utopian anarchy you should be prepared to deal with the consequences of exercising your freedoms.