If you do not think that life is meaningless without God, then any meaning you assign to life is only illusory Paradoxum, it is not real and is not based or founded in reality, for reality is that the universe is an accident brought about by blind random forces with no design, no purpose, no intent, no ultimate meaning, no concern.
Ask Nietzsche, ask Russell, ask Dawkins, what life is, I am sure they will tell you that it ultimately is meaningless and nothingness on the atheistic worldview.
Now, you can pretend that life is meaningful if that helps you cope with life, this is what atheists do, but pretending that life is meaningful does not make it so.
So at best, on the atheistic view, life can be meaningful only insofar as we give it our own meaning which is completely subjective.