I think that a problem that you have with this:
God has two basic answers: one is to point out some reasons why this is a good life (for example, it is how to be a human qua human, or something like that). If God says that, this atheist can return to the previous theist and give these reasons - which would be a sufficient justification for whatever moral system. On the other hand, God can reply, “What are you talking about, foo? I’m God, and I am Goodness, and I am the transcendent standard which is the only possible and final justification for morality.”
is that you have set up a false dicotomy. Where did you come up with the idea that there were these two, and only these two answers? I think that you have to take into consideration that, God being God, there are going to be things which HE understands fully which WE cannot, not now, not here. Human beings are not gods, and will not ever be gods in the sense that no human being will ever be an infinite, self creating omnipotent being,
One problem that you attempt to impose (so to speak) on God is insisting that He LIMIT Himself down to the very limited andimperfect knowledge of Joe and Jane Average Human Being by claiming that UNLESS He makes Himself absolutely and totally clear on point X, this proves He isn’t really God. When you think about this, really think, it is an absurd claim. While there is really no way to compare God with, say, Stephen Hawking, except to say that Mr. Hawking is made in God’s image. . .let’s compare Stephen Hawking to these three people: One is a bright 12 year old in an accelerated math program in New York City. One is a bright 44 year old businessperson in Uruguay. One is a bright 76 year old homemaker in Namibia.
Now, none of the three is going to be able to comprehend Mr. Hawkings in science. However, in trim the 12 year old may perhaps equal, or even surpass, Mr. Hawking’s achievements. The 44 year old may increase his personal knowledge, and further, the 44 year old may have business insights, particularly, which surpass Mr. Hawking’s in that area. Finally, the 76 year old homemaker might not even be literate beyond a rudimentary level, but again, her insights and achievements, for her age, sex, and location, might rival Mr. Hawking’s.
And this comparison is between human beings in one broad area. There is no human being who, across every aspect of human life, is so extraordinary or superlative that his or her actions, faultless, impeccable, brilliant beyond belief, in every breath of his or her life, could even be the merest atom like God. And there is no human being so perfect in knowledge or action that other human beings cannot meet, match, or even exceed those actions or that knowledge.
On the one hand you have those for whom humanity is “all”–even those for whom humanity is a limited, or even an ultimately doomed, degraded, and depraved all. If you limit yourself to this view, then you limit God to this standard, and, because of imperfect understanding in this way, either find humanity so “good” that the idea that God would limit ANYONE from heaven makes God into a cosmic blue meanie (therefore not god), or you find humanity so 'bad" that the idea that a good God could create such dreck makes Him into either an idiot who couldn’t “foresee” the future or some kind of puppet meister who gets his jollies watching people jump through hoops to please Him, then yelling" gotcha!" and sending EVERYBODY to hades just for fun. . .
On the OTHER hand, if you have those who think of humanity as a creation of beings with free will, made by a loving God who somehow has a plan, can somehow make things good even if we can’t understand (much as parents, in denying their children things which are bad for them are keeping their children safe, or who, rather than doing things for them, help the child learn to do things themselves, even when it is HARD work or the effort doesn’t get as good grades, or look as nice, etc), people who look about and see the good as well as the bad in every person, place, and thing, who try to increase the good, heal and help the bad, all in order not to just make things nice for themselves and their friends, but even for others, even for those they don’t like, even for those who don’t care. . .well, THERE you have a Christian view. It’s really both simpler and more complicated than I have set out. SImplest in the words of God Himself? Love God with all your heart, soul, mind, and strength, and love your neighbor as yourself–more complicated in that, as with any situation where you deal with fallible, yet lovable even in their fraility, people, you will have questions, questions, and questions.
Start by just trying to love God and seek His will. It won’t happen overnight–what worthwhile task or effort DOES?–and see what happens.