Part of the argument from personal experience, is that even if you can't work out whether God exists on your own, the question remains the same.
Some days you feel like you are sure, that God exists, other days you doubt it, that God exists - but throughout it, the question itself remains unchanged.
If there was no God, you would be as certain one day as you were the next.
And the end will come suddenly, you can ask God "can I question your existence forever?" the answer will be an emphatic "NO".