If all life evaporated from planet Earth tomorrow never to return, where is the value or meaning of anything you did or said or learned or contributed? It ceases to exist. It was all for naught. That is the point theists are making when they say that life without God is meaningless and without purpose. Whatever meaning or purpose you have as a human being is temporal. At some point, it will evaporate into nothing.
The finite aspect is what gives it meaning. To me, eternity is meaningless.
We live on this world as preparation for the next - but once IN the next, what meaning do we have then? What is the purpose of our lives once dead? Once ten billion years have passed, and our lifespans here are a long forgotten memory, then what? If the "purpose" in this life is "get to heaven", then do we have no purpose in heaven? By your terms, does that make heaven a pointless and meaningless state of existence?