I'd like to start out by saying we should all give the political leaders of the last 300ish years a boatload of credit and respect for keeping the nation as secular as it currently is. That was probably very difficult with an army of Jewish lobbyists, Catholic lawmakers, Baptist/Evangelical zealots, Protestant reformists, and Atheistic scientists knocking on the doors of the White House 364 days a year in attempts to further their various agendas. (Forgive me if I missed anyone, there are probably plenty I didn't think of.) We're a secular nation where the city still has to zone churches and approve the construction of private catholic schools. Logically there's going to be some disagreement in that kind of system.
The government represents the majority and protects the minority. Students are asked to say "Under God" in the Pledge of allegiance because the majority requests it and approves of it. They are not required to say "Under God" because the minority is defended, and no one is forced to believe in anyone else's God. If there are 10 Jews, 20 Arabs, and 50 Christians living in a city block and only one spot for a religious structure, the city will zone that spot for a church. This will mean that 30 people are left without a nearby house of worship, but 50 will have one. This is majority rule. By no means are those 30 required to convert to Christianity.
We learn about science instead of religion because the majority decided science was more relevant. Some people believe evolution is a fraud and creationism must be taught, some believe both should be taught. There is only enough time to teach one, so they teach the one the majority tells approves of. When the beliefs of the majority change so will what is taught.
The rights of private cooperations and entities the turn down employment or acceptance based on religion are loosely protected. If you sue a company for not hiring you because you are Buddhist, you will probably win. In theory, you should not, because as a free nation we should bear no involvement in the hiring practices of private entities. However, we are also a nation that disapproves of racism and hatred, and we have made a point of it by saying it is against the law to hate publicly.
Cities will organize Christmas parades and actives using tax dollars. They spend significantly more money supporting Christmas than all other religions holiday of the same seasons. They do this because the majority of people celebrate and enjoy Christmas. I don't celebrate Christmas, but I enjoy the celebrations regardless. The non-religious aspect of the holiday is free to everyone. If you have a problem with your city setting up a divinity display, that's really quite unfortunate, because for every one person that does have a problem there's 100 that don't.
Our society as a whole has lost the ability to see when it is a minority attempting to impose its beliefs. What if a city with 10 baptists, 100 Hindus, and 600 Protestants opened up a Baptists church because the Baptist lobbyists provided more money and rallied more fervently? This would be a selfish imposition, contradicting the teachings of most religions in the first place.
This is the point, America's government provides for the majority and protects the minority. We are a secular nation that will always, to some degree, provide for the currently dominant religions. It is the only method of leadership that makes sense.