Well atheists use logic, but when you ask how do you know logic won't change, why will we always use it or why use it. They say something like I just use do. Or in other words, the reason I use logic is I use Logic. This is called a circular argument.

If you tell an atheist the reason God exists is because the Bible (which is the word of God) says so. The atheist will say that is circular reasoning and has no meaning it is not good logic or something like that.
God is because God is.

The Christian has God who is unchanging never contradicts Himself and logic is the way or reflects the way God thinks.

So we can say we know this with certainty because God makes us certain of it. But they have nothing.
IF they give the reason to always trust logic is because they trust just trust logic.
We can trust God because we trust God is AND without Him there is no reason to trust logic.