God is always lurking around somewhere in the Bible. He's looking over your shoulder, blowing something up, or yelling at someone for not killing their ram on the right day. But look carefully, and you'll see that God is never really the same, even in two books as closely related as say, Exodus and Deuteronomy. In Exodus, God is super direct and actually gets some physical screen time. That's right—if you were to cast an Exodus movie, you'd have to pick an actor to play God.
Deuteronomy is a little more complicated. Sure, God is in the picture, but it's mostly just Moses talking about God, or God communicating with Moses using who-knows-what method. Why? Well, cultural views about God were changing when Deuteronomy was written, and so the characterization of God in the story also gets tweaked.
Essentially, Deuteronomy was written after some kind of cultural catastrophe (or group of catastrophes—we can't be sure) and people thought God had abandoned them. Given the context, the writers shied away from a God who was directly involved in their text. He's there all right, and we'll get into that in just a second, but be careful to pay attention to the way he's there.
Let's see—hailstones and lightning bolts? Yeah, we're going to call this one angry deity. After all, God would have destroyed the Israelites if Moses hadn't intervened. He punished the Israelites who refused to fight for their Promised Land, made them wander in the wilderness for forty years, and eventually let them die without ever reaching their goal:
"The Lord will scatter you among the peoples; only a few of you will be left among the nations where the Lord will lead you." (4:27)
Ouch. Talk about an intense punishment. Wasn't this the guy who promised everyone free drinks? We pity the fool who crosses him.
But let's not get ahead of ourselves. After all, this same guy gives laws that talk about taking care of widows and orphans and reminding the Israelites to be kind to strangers:
"For the Lord your God is God of gods and Lord of lords, the great God, mighty and awesome, who is not partial and takes no bribe, who executes justice for the orphan and the widow, and who loves the strangers, providing them food and clothing." (10:17-18)
Civic leader, community enhancer, and compassionate companion. This is the God who created puppies, kittens, and butterflies. He's the kind of guy you'd invite over to your house for dinner. (Leave the brimstone at home, please.)
So we end up with two competing portraits: angry God and compassionate God. But maybe this is exactly what God's going for. After all, being seen as both universally merciful and universally vengeful is the ultimate form of power. Even Machiavelli agrees.
P.S. Did you notice that God's anger never really gets invoked unless people mess up? It's a lesson to the readers to follow the law—or else.