If Islam is a religion of peace why did it expand through military conquests?

[Sword of Christ]

Providing for widowed women? Firstly, these weren't widows. They were virgins.

Virgin can mean young woman in Hebrew not necessarily a literal virgin. Their village would have been destroyed and their men folk killed so of course they would have needed some man to look after them in a home where they do their household choirs and what have you, their natural element where they belong.

, and the only reason they'd have trouble finding men is that someone came, killed her friends and family, stole their stuff, and dragged her off to be raped.

We're talking about tribal wars and the division of the spoils women included. There is a cultural/historical context that is a little different from our own. Morality has changed but I would claim for the better and for a good reason.

Then if she didn't satisfy him enough he could shave her head and throw her out on the street.

That's not quite how it worked. What happens is her head is shaved, she is given a period of mourning where she is not to be "known" by her new husband. If shes not happy about the situation after this period she can leave and not be sold into slavery due to the dishonour she suffered. Yes it's not really what we would do all the same.

It's because I'm not making excuses for a god that lets current human culture dictate what he says is right or wrong.

There is a right and wrong, a good and evil and we understand this on some level. We don't always get it exactly right but we know it's important for some reason. We have an inner sense for this, Mere Christianity is a good book that fleshes this all out. Otherwise what you're left with is "opinion" which can be anything and is meaningless. No-ones cares what your opinion of morality is only that you are moral.

You have this conclusion that Yahweh is a good person

No God is the foundation of what good actually is not a good person. You're good if your action draws you closer to God and evil/sinful if it draws away from God. God is the benchmark and the measuring stick, God is your conscious, the quiet inner voice the guiding point.

, so any time his actions don't fit what most civilized people believe is right, you have to make some sort of excuse for it

Flawed sinful humans wrote the Bible and communicated on Gods behalf and so there is plenty of scope for some miscommunication. Jesus message somewhat more pure as in him you have God speaking directly without an intermediary.

, or maybe say he's mysterious and incomprehensible like other people have said. Incomprehensible, but undeniably good somehow.

If you want to know what Gods standards of morality are then listen to what Jesus say, seeing as Jesus is God.

It's a confusing book that can be used to justify pretty much everything.

The New Testament/Christ should clear up any misunderstandings. God saw that this was a necessary amendment.