Sorry to burst your secular bubble but the problem IS secularism. That fact that you even use a phrase like "separation of church and state" which is not in the Constitution just shows how well the libs have succeeded in framing the debate. To paraphrase Nixon: "We are all secularists now."
That's your entitled opinion, and you are welcome to it. We don't really want to argue about it since neither of us will budge on our own interpretations of the first amendment.
What is the real problem?
The radical secularists want to strip culture from our government. Their motivations are much broader than simply avoiding religious establishment or preference for one dogma over another. They actually want to replace our culture with a new one, and their tool is the government. They want to turn our society into Hillary's proverbial Village, and enact radical changes in our value structures and moral underpinnings. To complete this task, they understand very well that any vestige of religion, which is an arbiter of culture, must be removed from our civic procedures and ceremonies.
The Village proponents are like the Puritains of old, who wanted to achieve a utopia on earth through American life. They are well aware that a vacuum of culture must be filled, and they are already stowing their dogma into our laws and politically correct codes of behavior.
Shouldn't we sit up and take notice? Shouldn't we do something about it? Yes, but with careful consideration to our actions.
The government should follow culture, not drive it. The Founding Fathers knew that. The radical secularists do not. We of all people should know it. The answer is to explain the situation in terms they can understand, and then ask the people to decide. I am in favor of a constitutional amendment to clarify what the the term "marriage" means to Americans. This is not an establishment of culture (or religion) by the government -- it's a reminder for those who would so quickly forget.
Meanwhile, I suggest you put your religious zeal to work in convincing the churches to teach biblical values. Our cause will be realized much more quickly if the churches remember to teach what's written in the bible. How can you expect spinelss civil servants to adhere to cultural values that the churches are undermining every day?