The big difference between the Amish, and evangelical Christians, is that many Christians are extremely vocal and often confrontational about pushing their beliefs on everyone else. They also cynically claim that anything they don't agree with violates their religious freedom. What you call 'supporting gay activities' in practice translates to evangelical Christians demanding to revoke that freedom from everyone else.
" No one seems to want to challenge the Amish on their traditional values"
That's because they don't insist on pushing their 'traditional values' on everyone else.
What many Christian claim is suppression of their 'rights', is really people (rightfully) pushing back on the Christian desire to turn the country into a theocracy, like a Christian version of Iran, with a Christian equivalent of Sharia law as the law of the land.
To hell and back with that BS!
What you should be pointing out is that unlike the extremely loud, meddlesome and downright obnoxious self-proclaimed Christians screaming on every corner and trying to ram through all kinds of theocratic nonsense in legislatures that deprive citizens of their rights, the Amish generally don't engage in this kind of thing.
I'm not Amish. I'm not even religious. But I admire the Amish because unlike many Christians, they seem very content to practice their religion in peace, and they don't seem hell-bound and determined to petition for a bunch of laws that mandate that I adopt more 'Amish' morals.
They might not believe in using smartphones or the internet, but - to my knowledge and in my personal experience - they've never once demanded that some law be made banning the modern things they don't like. That's the fundamental difference.
The Amish also aren't endlessly annoying by pestering you to convert to their way of life, unlike evangelical Christians who believe that their salvation in heaven is dependent on you accepting their 'gospel' and converting to their church.
One article by an evangelical I recently read even claimed that HIS religious rights were being violated if we didn't convert to and follow HIS religion, because his failure to push his religion on us meant eternal damnation for him, and thus by not accepting to join his church, we were dooming him to damnation and violating his rights. Not even joking. There are Christians in the US that really are THIS fanatical and it's extremely dangerous because this is essentially the same strain of fundamentalist extremism that drives ISIS, Jihad, the Taliban, etc. with their 'convert or die' mentality.
On the other hand, I've never, ever been badgered or confronted like this by an Amish person. I sat next to one on the train once. He was chill. Very friendly. Willing to answer my questions about his lifestyle. But, never once preached to me about needing to adopt his morals or values for myself. And he didn't threaten to vote to take away my rights.
This is what freedom of religion should mean. You do your thing. Leave others alone that don't want to do your thing. And don't try to ban other people's things simply because you don't like them.
The underlying idea of the US was NOT to be a theocratic nation, but a secular one, with the government staying out of the business of playing favorites or picking winners or losers.
Capitalists want the government out of the market. They have the good sense to not want the government to 'pick winners and losers'. Why then, should the government meddle in such a way when it comes to religion?
Once you start trying to decide which religion the state 'officially' supports', its game over for civil liberties.
I'm sure the Christians would love for their governments to pick a religion to officially support, assuming it would be theres. But what about in areas (like in Michigan) that are majority Islam. What if they want Sharia law as the law of the land? Would Christians be thrilled to stand up and champion this? I doubt it...
Just because gay marriage might be legal in some places doesn't mean its being forced on Christians who don't want to enter into a gay marriage. If you don't like gay marriage, don't marry someone of the same gender. Easy. No one is forcing you to enter into a gay marriage, or any marriage for that matter. You still have a choice and that freedom. Fanatical religious zealots want to take that away.
If the Amish don't like cellphones, then they can simply not buy a cellphone. We don't need a nation-wide ban on cellphones to appease the Amish.
Likewise, I don't think the government should ban books, abortions, homosexuality etc. merely to appease the Christians.
The founding fathers of the US didn't seem to think there should be states-sponsored official religion either and they were very wise in this regard.
Finally, I find rogue4gay's assertion that separation of church and state is impossible comical and absurd, because there are many other countries in the world that abide by this idea of a secular state allowing religious freedom. This is not merely an 'American' concept. In fact, the US does a pretty poor job compared to countries like Albania, that have a diverse (and peaceful) religious landscape with no recognition of an 'official' one by the secular state.