Sea Breeze: If, out of our own free-will we ask God to give us the new nature he promises, one that cannot sin
It doesn't matter if we want it or not, either way we are not the same person afterwards. You yourself describe this as our nature. If we change that, we change an integral part of ourselves, don't we?
Sea Breeze: The removal of the sin nature doesn't make sin impossible or render us incapable of independent thought or action.
But, you said above that the new nature is one that cannot sin. Indeed, this raises the question of how this sinful nature works: Did Adam and Eve have this nature? Did Satan? Did the angels who later joined him? If not having a sinful nature means we can still sin, what is the difference in having or not having it? If not, why would god burden humanity with it?
Sea Breeze: This is the primary purpose of man - to love God
A being of incomprehensible power creates a massive universe so that the can put humans on a vanishingly tiny speck, whose primary purpose is to love him. This does not personify love, it personifies narcissism. How can I have value in this context, where I am created primarily to provide something that god could do without? And where, no matter how much I love him, a misstep might lead to eternal suffering?
Sea Breeze: So, you think that the origin of morality is a convention?
I don't know what the origin of morality might have been. It's development has been a process, which continues now and will probably continue for a long time yet.
Sea Breeze: The problem is that the atheist cannot account for it with his stated worldview. It violates his own presuppositions of chaos, happenstance, copying mistakes and chemical accidents.
I did not become an atheist because I decided that there was an alternative. I was trying to prove god because I was sure he existed and I wanted a way to convince others. I realized I could not do so without presuppositions, which meant I didn't really know if he was real. My worldview changed relatively little after I realized I did not believe in god. Most of the refining was in understanding that being an atheist meant that I rejected those models or concepts of god that I could not make sense of.
The atheist worldview consists of one point: I am not convinced that your god exists. That's it. That's all. Some people will express more doubt, and at the other end are the diehards who insist that god isn't even possible. What they share is only that one point. Maybe there are some who have decided that it's all chance and chemical accidents. I don't know enough to say. You imply that the only alternative to god is an impossible scenario. Perhaps you are right. I know only that the god you describe is even less likely than chance and chemical accidents.
I didn't replace my resuppositions when I stopped believing in god. I dropped them. That means I have to admit that I don't have some of the answers, and I can't allow myself to cheat by making them up. But it also means I am not satisfied with accepting a starting point that I cannot determine is true.