That explains WHAT? The existence of everything is explained by "Everything equals zero"?
No, now *explained*, *allowed*. And it isn't 'everything equals zero', but that the total energy is zero.
In other words, it shows that your bringing up the conservation of energy is an invalid argument.
But we can go further. Technically, the conservation of energy says that the total energy of a system at one time is equal to the total energy at a different time: the total energy does not change.
And, even if the universe had a beginning, that would still be the case. It is possible (even predicted by general relativity) that time simply cannot be extended prior to the Big Bang. In other words, there would be no violation of the conservation of energy because there was no previous time to do the comparison with.
But, there are other possibilities. For example, in most versions of quantum gravity, the Big Bang is a type of phase transition between the universe now and the universe that existed prior to the Big Bang. And that prior universe existed infinitely far back in time. Hence, there again would be no violation of the conservation of energy: the total energy would have been the same for all times.
That sounds like atheist/materialist philosophy all right. Christianity says everything has profound meaning.
OK, but that is irrelevant to your argument.