How to easily defeat any argument for God

[GrandizerII]

It's not a consensus, it's nature.

There is a current consensus about the best way to achieve wellbeing, more or less. This can change quite a bit. The consensus in different times and places can be pretty different. Maybe it's nature that we aim for wellbeing, but concepts of what that consists of and how to get there vary.

That's what I meant. Behaviors aimed for wellbeing would've generally been favored by natural selection.

As for the specifics, agreed, it's different variations (based on varying circumstances) but still boils down to something to do with wellbeing and such.

People aim for good because that's how we've evolved via natural selection. 

This begs the question that what is good is the same as what natural selection made us consider that we want. If you say that the contingent preferences we have due to natural selection is exactly equal to what's good, then what you say is true. But I think that's awfully close to the appeal to nature fallacy. It's possible that natural selection gave us all kinds of preferences that we find it more moral to suppress. 

It would be safer to say that practical steps toward our evolutionarily decided preference are expedient, given that goal. Whether they are good or not is a separate question.

But if good is linked to wellbeing, then natural selection would've ensured that over time we (as a species, not individually) would be motivated enough to do what's good, even if in a tribalistic manner whereby we are selective of who we generally do good to. Need to go now, I'll see if I need to elaborate more later.