Now, I come at this from a Christian first perspective, which the founders did as well.
Their politics did not trump their Christianity, quite the opposite.
It was their Christianity that framed their politics and allowed them to create the best government system in the history of the world.
And yes, the Federal government can enforce Pro-Life laws and enforce Anti-Gay Marriage laws quite easily and effectively. There is no difficulty there.
What you have presented is a straw-man argument.
To mix the political framework of freedom from government interference with individual framework of his freedom to choose is fatal (not to mention unconstitutional which doesn't seem to bother you). Government does not give man the rights to life, liberty, and pursuits - it can only protect them - and that is basically the only role of government. Once you give central government power over individuals' inalienable, God-given rights, you turn the American revolution into the French revolution and citizens' heads roll or the USSR which had a huge list of a bill of rights (under the power of government) and tens of millions of its own citizens were killed by it's own government.