I would ask you why an all-powerful creator would bestow us with an inherently questioning mind (that by nature seeks verification in order to establish the truth or falsity of our beliefs) -- and then punish us with horrific suffering if we used this same mind to question His existence.
Let us assume that your question is quite right -- and I do. Did an all-powerful creator do these things to you or me? I don't think so.
On the other hand, it is true that scientific verification is a long way off for our beliefs about the purpose of life. In Carl Sagan's CONTACT (the movie) the aliens reported that they had concluded after long experience that only thing that made it all worth while was "each other." Now if we include the Creator in this little circle of love -- whether you feel the Creator is within you and me and others or external -- we at least have reason to love the Creator. If we feel there is a time when our circle of love ain't workin' so well, there is reason to attempt an activity something like worship AND maybe it could be done in better ways. The sacrament of communion seems like a partial observance. Something more is needed.
Can you help? Does a skeptical sincere person have good reason to believe in the type of love just described?
If God exists and He is truly omnipotent and benevolent, why doesn't He simply offer us some irrefutable evidence of His existence, thereby saving many souls that might otherwise be damned? Why are parting seas and burning bushes only found in the ancient texts? A single incontestable miracle would be sufficient for me to change my beliefs.
You have won a big part of this argument, I believe, by inquiring honestly. One possible answer to the question is that the idea of an omnipotent and benevolent God might be one who
can change the rules of your board game WHILE WE ARE PLAYING to let us win...but then the game we were previously playing is over. Do we want that? Very well, let us begin a new game!
But I do not insist there is an omnipotent God who stands by waiting to be called upon. There is however, LOVE, and yours is probably essential to the circle.
In the Courses in Miracles, a change of perception itself is counted as a miracle.