Haven't you switched the argument from that which we redefine to be God to about the God that we've redefined?

Sure, but your attitude isn't really shared by a majority of people, which is really the root of this question, no? For people to accept that there is no soul, you'd have to teach them first to think objectively, to be unafraid of letting go of what we think we know now and search for evidence, for real fact. Which is really quite a difficult task.

Or maybe now is the time to redefine what we believe to be a soul?

I guess it doesn't really help us learn, become more advanced people, and I can see why that could be sad, but what's moving forward if we don't feel satisfied with it? At least, that's what I make of it all.

I like to believe that we're more than the makeup of our brain, sending electric impulses, and our genetics and personal experiences.

As in, if someone were to somehow replicate all that of someone I knew and replace them with the copy, that wouldn't sit right with me. The copy, however well made, wouldn't feel the same (like it's a different soul). Of course, you wouldn't even notice a perfect clone replacement, being a perfect clone and all, so this feeling doesn't really hold up against logic, or anything really, apart from my irrational heart. But who wants to think that, once (if?) we reach some technological level that allows this to happen, we can just just keep replacing each other?

It's just a nice, probably ultimately wrong, thought. But nice all the same.