Answer: God alone is infallible; for “infallible” means one who cannot fail. Truth is not the same as infallibility; truth is the opposite to error, not to fallibility.
Scripture comes from God; it presents the truth; it is infallible. But there is no need to defend it to the infidel who rejects it. However, There is a difference between infallibility and perfect truth. If I question the infallibility of scripture, I am making a statement about the book. However when I reject perfect truth, I avoid facing what affects my conscience.
In strict logic, only one who is incapable of erring, is infallible in what he says,