There is no free will from a pure science position, since everything works by cause and effect.
God, for His own purposes has held a tiny bit of free will open in people. This little piece of free will has to do with the strength of faith that a person has in God. That's it. It doesn't have anything to do with anything that we think about in life. And even this tidbit of free will is regulated by God to some extent.

No no no, that won't work. You cannot pick and choose free will out of your arse when it suits you.
Christianity relies on free will. Without it people cannot ask for salivation, rendering Christianity false.
So take your pick:
1) We don't have free will. Thus Christainity is false.
2) We do have free will. Christainity could be true.