Humans evolved with some baseline level of morality to be able to function as tribes/societies etc. You could argue it was an evolutionary process or that humans were imbued with an innate sense of morality by god. Just because you could argue that there is a baseline sense of the concept of morality in humans it doesn't mean that logically follows its attributable to god.
The problem is that Christians cannot provide sufficient hard scientific evidence for their belief in a Christian god.
Any scientific evidence would be automatically rejected by you as being impossible, and you would justify this as saying "I have no alternative explanation but Science will explain it someday." Creation itself is scientific evidence of a Creator which you ignore when it's raised despite lacking an alternative Scientific explanation. It may not PROVE the Creator but it is absolutely evidence to any nonbiased person.
Science is building a 'best model' based on our observations. It appears to me that you ab initio dismiss the existence of the Christian God as an alternative possibility to his nonexistence. You prefer your own faith that Science will eventually come up with alternate explanations that don't involve God. I used to approach this topic the same way when I was an atheist and it led me to speak like you. I don't mean this in a condescending way though I'm sure it comes off like that.
The Scientific atheist has no Scientific explanation for existence, there no Scientific explanation for the origin of life, there is no Scientific explanation for the advanced consciousness that separates men from animals. And there never will be, this is not the role of Science. It is the role of spiritual revelation to man's heart.
I am just humble enough to admit I do not have the answers.
Right underneath your post, GodfatherPartTwo explain how Christians in fact acknowledge, in submission to God, that they do not and will not have all the answers regarding the exact details of God's plan for humanity's salvation. It is you who is demanding all the answers. Don't get me wrong, your questions are fair and I invite them. But if you are actually interested to explore Christianity and not just debunk it (by all means clarify because I'm not interested to engage with a deboonker), you have to "try it on," so to speak.
I don't want to pile on you Australia cause I know it's only you on one side of this discussion against an entire forum of Christians, and while I've been harsh to you, I see a lot of my younger self in you as well.
Here is my absolute most important advice I could give you if you want to understand the truth of Christ:
You have to willfully force yourself accept the possibility of God's existence as true, even if you consider it to be a temporary experiment. Then read the Gospels (they're not long and quite readable), visit a Divine Liturgy (even if you simply view it as an experiment). This will start opening up all sorts of insights into the truth. I know it's a lot of work but it's only the meaning of human existence, it's fair to expect some effort to be involved.
On the other hand if you refuse to truly, in your heart, be open to God being real and Christ being His son, it's purposeless and will only strengthen your atheism. I know this firsthand.