As a Unitarian Universalist, I can be an atheist (30% of us are) and be in relation with Christians, Jews, pagans, and people of many other beliefs. Couples with different beliefs come to our congregations. It sounds like the original poster's husband is a fundamentalist Christian, but many Christians are not fundamentalist and some can change from fundamentalist/conservative to liberal. There's even an Episcopalian priest in my church who married a Unitarian Universalist. I don't think her beliefs are Christian, but he says his are even though he fully embraces our principles (he says he's a trinitarian and a unitarian even though they seem contrary, but he says it's metaphor) and he will not try to compell someone else to be Christian. None of the UU Christians try to compell others to believe the same way they do. I have met many other Christians who are the same (Quakers, even liberal Catholics).
I'm not saying that there are no fundamentalist Christians who try to convert you - there are plenty. But the atheist who does the atheist.about.com web site is married to a Christian woman and that's why he didn't go to the Godless American rally in DC in 2002, but I went. I emailed the organizers and got a message from the president, Ellenn Johnson at the time, and she said that even though I was a UU who considers myself an "agnostic" that I could go to the march, but she didn't want Christians there. The host of atheist.about.com protested because he couldn't bring his wife.
Just saying, not all Christians are the same and atheists and Christians can be married.