Well, that's the equivalent of putting your fingers in your ears and saying "lallalalaa I can't hear you!"

edit: In other words: you should not just choose to "believe" one thing or another. You should look at reality and decide what the evidence favors.

Otherwise, you don't really know, and you know that you don't really know, and you are flying blind in life, and thereby engendering in yourself a sense of helplesness and anxiety (no coincidence that one of Sartre's works was called Nausea...).