rational naturalism is impossible!

[Chas]

for my first post actually arguing for something, I decided to do something new. i'm using an argument I haven't seen here yet and one I think is very interesting. if you would like more details on it, it is an argument developed by Alvin Plantinga in my own reiteration.

instead of arguing a proposition is true or false, this argument concludes that it is impossible to rationally accept naturalism. here are the reasons for this:
1. P1 if naturalism is true, then there is nothing beyond our physical selves.
2. P2 evolution is a process that operates with the goal of survivability.
3. C1 our cognitive functions have come into being by the process of evolution- from P1&P2
4. C2 all our cognitive functions came about for the purpose of survivability which is not necessarily hinged on determining the truth- from P2&C1.
5. C3 we have no way to know if our reasoning leads us to truth in any proposition including the proposition of naturalism itself. any and all propositions based on our cognitive faculties (which are all of them) then are just as likely to be correct as they are to be incorrect- from P2&C2.

conclusion: it is impossible to rationally believe in naturalism. the very concept of naturalism entails the possibility of our cognitive faculties being unable to reason truth, which includes all truths including naturalism itself. it's self defeating. and before someone asks why this doesn't apply to religion like Christianity, the answer is P1 isn't a claim of Christianity and in fact is inconsistent with Christianity. if P1 is false, then C1 doesn't logically follow. a Christian can simply claim their cognitive faculties are indicators of truth by the intent of our designer.

extra notes- before i'm misunderstood I want to make it clear, this argument is not formulated to prove naturalism is false. I hope to see no one who interprets it that way. it is only meant to show how it is impossible to rationally believe it for the reasons in the argument. it shows that presupposing naturalism is true entails the best probability for all our beliefs to be correct is 50/50 since we can't know if our cognitive faculties are in fact indicators of truth. that is it.

P2 is not true, your argument fails.