the poll provided clearly says that the people in support of gay marriage are Liberals young people as well as nonreligious it says it right in your survey. Also people argue if America was a Christian founded Country... it is obvious that it was a founded as a Christian nation but non the less people will argue it so even if you deny that it is undeniable that is was Religiously founded.
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.--That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, --That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness. Prudence, indeed, will dictate that Governments long established should not be changed for light and transient causes; and accordingly all experience hath shewn, that mankind are more disposed to suffer, while evils are sufferable, than to right themselves by abolishing the forms to which they are accustomed.
Tell me a "NONreligious" group that believes in a creator?
if there is none which there cant be for obvious reasons then you apply simple logic and say that the founding father were religious and based off of that and knowing even with your numbers that religious people are not Pro homosexual marriage you can also know that our founding fathers would have been on that same boat.