OK, I’ll try.
First, there is the “fine tuning argument”. It starts with noticing that there some things that had to be exactly as they are in order for us to exist. For example, if the physical constants were just a little different, stars wouldn’t have formed and, of course, there would be no Earth and no humans on it. Now, if the constants were chosen at random, or (what is mostly equivalent) they just are what they are with no explanation, it is much more likely that we’d end up with a “wrong” set. But we ended up with a “right” set, thus it is likely that it was chosen deliberately. And then we can ask who could have chosen them. As you can see, this argument does not say anything about how God maintains the universe in existence. But it does lead one towards existence of “original” creator or “designer” of the universe.
Second, let’s see what would happen to this argument if we knew that “multiverse” exists. Then we have many universes. Let’s say that each of them can have different physical constants. Then we only need one universe that holds us to have suitable constants. And one “lucky” universe out of many is more likely than one out of one. Thus the premise “It is very unlikely that the randomly chosen physical constants would have been compatible with life.” becomes weaker. With it the whole argument becomes weaker.
Third, other arguments are not affected. Actually, at the moment I don’t know what to explain there…
So, is that clearer now?
