Logic puzzle: deductive entailment

Since it's not established that A and C are friends, no.

Assuming, as Aristotle did, that either "B is Christian" or "B is not Christian", yes.

to apply logic you can not have an unknown element ...

NerdGirl123 said:

Since it's not established that A and C are friends, no.

Click to expand...

Whether B is or isn’t a Christian, ypu end up with a pair where one is not a Christian.

The question is "is there a Christian with at least one non-Christian friend".
The only established Christian in the group is A.
The only established non-Christian in the group is C.
There is no direct connection established between A and C.

Sparagmos said:

Whether B is or isn’t a Christian, ypu end up with a pair where one is not a Christian.

Click to expand...

I do believe you've solved it.