How come theists can't answer conditional questions (ones starting with the word "if") but atheists can?

Theists will say something like "Well, I don't have to worry about that, because existence is impossible without God!" or something equally as stupid. They might throw in the "You'll burn in hell if you don't believe!" card and spew a bunch of Bible quotes thinking that reading parts of the Bible are going to convince someone to believe in Abrahamic God, like the Bible is the ultimate source of wisdom and is infallible. Atheists seem to be able to answer a conditional question. They can admit that they're wrong if they're proven wrong. Theists haven't proven atheists wrong so far. Is being unable to answer a conditional question a sign of narrow-minded thought? I mean, being bombarded by a load of conditional questions can make someone annoyed enough to skip it, but just one isn't really so bad, is it? All people have limits.