You are making the assumption that belief in God is necessary and that concepts like morality, purpose and meaning, are possible only if such a deity exists. You obviously feel that god is not only necessary for life and for it to have meaning and purpose. You are saying the universe does not establish purpose to our lives
I totally disagree with your premise. We create our own meanings and purposes. This is much more significant "purpose" than one directed by a being that doesn’t even bother to communicate directly, unambiguously or coherently to its creation. In fact if you don’t create your own purpose and accept a purpose or meaning imposed by someone else, is that not slavery?
The reality is we find it impossible for meaning to be imposed on us by someone else. I can’t make an event that has meaning for me create the same emotional state for you. The reason why is because you need to have experienced the event for yourself. The emotions and the interpretation of that event were processed by my brain, and it was my brain that created the memories that induce the nostalgia that is so important to me. Those memories that I possess will never have any meaning to you. That experience has value to ME, I cannot infer that value to you! Values cannot be imposed upon us because they must develop out of our character and our personality; so if meaning is derived from values, then meaning also cannot be imposed, by anyone or anything especially an invisible man / woman in the sky.
Your concept of god has meaning for you because of a choice you have made, you cannot argue that the value or meaning your concept of god can be created for anyone else. The value you assign to the god delusion you possess cannot be inferred to anyone else.
So if in your opinion a personal meaning or purpose is impossible and an objective meaning or purpose cannot exist without a god that is your opinion and has no relevance for anyone else. You may feel depressed by the thought that I do not share your delusion, but that is your problem and not mine! Even if I did find the randomness and eventual destruction of the universe depressing what does that change? Since when does a an individual adopt beliefs about the state of the world or the universe based upon what is least depressing?
Meaning and purpose in life has no bearing on the reasonableness of either theism or atheism. If your concept of purposes is predicated on your belief in a god - good for you! I have many delusional friends who feel this way. However, I make my meaning around my friends, family and ambitions. I am fully content knowing that the conscious state I enjoy is only temporary and is a miraculous thing. I am one of very few entities to have enjoyed this state of consciousness and I am determined to make the most of it by making this life worthwhile to me, my family and anyone / anything else I can influence.