Of course you do.
ā¦How do you know "that there is a God and only One God as described in the OT? "
What empirical proof do you have of that? WHY do you believe it?
Let me start with how I know that there is some form of god at all.
Statistically speaking, I find it highly unlikely, if not downright improbable, that we could exist as we do by a series of acts that are each long shots. This applies to the nature of the earth, the nature of the solar system, and the way life exists. Though it is not impossible for life as we know it to have developed on its own, the fact that it is against such odds that the other possibility, that the universe was created and life was placed on earth, seems more likely.
Now, I accept that it is likely that there is some higher power that put it all together. Is it possible that this (or these) powers started it all and then left? Yes, but I see evidence to the contrary. First, there are religions all over the earth, leading me to think that there is something within the mind of man that craves some form of faith. Some could say that it is the fear of the unknown. Others could say that it is a desire to have something bigger than us to hold us together and force social morality on us. I see another option: the creator or creators of the universe desire a relationship with us and so we were hard-wired with an innate desire to worship.
Alright, someone put us here and they want us to worship them. How can we know who this is that did it? First, the likelyhood of a pantheon is right out. There is too much order, too much symetry in the universe to have gods that have conflicts. Sooner or later, the sun god would be mad at the water god and we would have a problem. Now, is it possible that these gods are of the same purpose? Yes, and they may never fight? Yes. So I must find another option.
From what I have studied, the creation story in the Bible is the only one from ancient peoples that did not have the universe created from a struggle. All others, that I know of, have it created from war or from some sort of sexual union that ended badly. Why is that important? Because it points to something that the other faiths do not claim: one God who is all-good and all-powerful, all-knowing and eternal, who is Love. Now, this God, according to the text of those who worship him, desires a relationship with us. He goes so far as to helping his people by creating a nation and a religious system for them. This God claims to be ONE AND ONLY ONE God.
So, by this, I accept the claims of the OT God. You are welcome to disagree.