They are free to _WANT_ to block gay marriage. However they are not free to _ACTUALLY_ block gay marriage.
Firstly, no one is claiming that Darwin is supernatural or correct in all things. Second, who here isn't quoting Darwin when asked?
If something is perfect, it doesn't need to change.
If your claim is that the Bible is the inerrant word of God, then of course I can.
If your claim is that the Bible is an accurate depiction of events, then of course I can.
If your claim is that God's "creation" is perfect, then you are in for a VERY big surprise.
....or else the "loving" invisible sky wizard will punish you forever in the fire pits of Hell which Dante' invented in pop literature.
So, you believe that Adam and Eve rode dinosaurs exactly like the the Flintstones?
You believe that rabbits are a kind of cow?
You believe that prior to the Flood everything was in black and white?
You believe that T-Rex was a vegetarian?
You believe that on a bet, God let Satan kill Jobs entire family because Job was TOO FAITHFUL to God?
You believe that God deliberately murdered the children of Egypt as part of a twisted game he was playing?
You believe that there are other deities who grant magical powers to other people?
You believe that the Earth is flat?
You believe that everyone on the planet is descended from incest?
... that's a lot of believing.
And the Bible does not claim these things. It is people like Believer (falsely so called) that try to put words in God's mouth.