I'm glad that you like America better than India. But you seem to be attributing that to Christianity. See if you can identify what parts of America you like, and ask your Christian girlfriend to show you where they come from in her bible.I have a Christian girlfriend and I don't care if she goes to church or raise our kids as Christians, if we decide to get married. Life is far better than India, where Hindus keep oppressing its minorities and murdering them in thousands especially in the Punjab and Kashmir region ... Yes I believe in secular govt and religion should be kept privately in their own homes and thanks to America for that.
For example, the secular government that you just thanked America for. Do you think that that is a Christian value? Let me share with you their first four Commandments:
 I am the Lord, your God.
 Thou shall bring no false idols before me.
 Do not take the name of the Lord in vain.
 Remember the Sabbath and keep it holy.
Christianity's model for government is theocratic. Secular government is a secular humanist value, not a Christian one. The Christians are continually trying to erode the secularist wall that separates their church from everybody's state, as they are now with their attempts to pass an amendment to the constitution forbidding marriages other than those that their priests say their god endorses.
What else do you like about America? Freedom? democracy? Egalitarianism? Limited government? Ask your girlfriend to show you where those ideas can be found in her bible as well.
You might prefer to raise your children without religion, especially if you think that they might like a career in the sciences. Have you heard about Christian schools? They have their own textbooks for science that are illegal in public classrooms. Seriously.