I thought current theories had a beginning, where even time began.
To the best of my knowledge the beginning referred to relates to what preceded the big bang, a place where science cannot go. The sort of thing one hears is that our universe is part of a bigger universe, that it came about as the result of an event in another universe and so on. In some such sense one could argue that that our universe always existed. It can also be said to have come into existence for reasons not known to us. A cosmoligist might be able to offer you clearer answers.
None of the above makes any sense because it is beyond our comprehension But so, too, is the idea of an uncaused cause i.e.. god. That answer means that god always existed which is contrary to the proposition that everything has a cause.
Worse still, theists are not prepared to leave it at that. They would have us believe that god has all sorts of ( human) attributes, that he/she has plans for us and demands certain things of us. This leap is made without a shred of evidence; it simply satisfies a need to believe in something greater than ourslves.