I'll admit this is an area that I will probably have difficulty combating any particular passage. I'm willing to give it a try if someone wants to ask about any specific verses or story, but it's possible I won't have much of an answer without studying it a bit.
I'll give it a shot. Explain the ten plagues in Exodus, which includes the death of innocents' first born. It seems pretty easy to describe him as a "vindictive, bloodthirsty ethnic cleanser" after reading that stuff.
Sorry, I don't know how to do this in just a few words, so here it goes...
This certainly isn't an attempt to make anyone feel good about the death of a bunch of firstborns. But, once again, I think it's helpful to think of the story aspect here. God decided he wanted to work through a group of people as his vehicle to rescue all of creation. This mission all flows out of Genesis 12:3 and the descendants of Abraham. God needed his own "firstborn" to form a special relationship with him so they can really get to know him and then they can be the way blessings come to the world.
The picture at the beginning of Exodus is that this family that God is going to work with is being oppressed as slaves in Egypt. The Pharaoh's plan is to wipe them out. So, what God sets out to do is rescue his people so he can continue the mission of fixing this big mess we are all in. God's first attempt is to simply ask Pharaoh if his people can take a few days to worship their own god. He does this by declaring "Israel is my son. My firstborn." And there's a warning that the refusal to let God's firstborn go will lead to the death of "your son, your firstborn." Pharaoh, of course, refuses, and increases the oppression of the Hebrew slaves.
But God doesn't jump straight to wiping out Pharaoh's firstborn. Through signs and plagues, God displays to Pharaoh that this is a losing battle, basically begging Pharaoh to make the right decision. God wanted Pharaoh to recognize who he was and that there's a better way than the Egyptian gods and the oppressive empire he built. Sure, I guess God could have just beamed the Hebrews from Egypt to Canaan Star Trek style, but he didn't. Why not? Because the only goal wasn't to get the Hebrews out of slavery, it was also to change the hearts and minds of the Egyptians. He didn't just have mercy on the Hebrews, he also had mercy on Egypt by slowly taking down their gods and their Pharaoh one by one.
But there's the tricky issue of God hardening Pharaoh's heart. It seems like Pharaoh didn't even have free will and God was dead set on killing his firstborn all along. First, the text bounces back and forth between whether it was God doing the hardening and Pharaoh doing the hardening. Aaron and Moses use three signs before the plagues even start to try and convince Pharaoh. During those signs and through the first five plagues, it's all Pharaoh doing the hardening. He's the one standing in the way of a peaceful resolution. Then in plague six, God does the hardening. However, English translations take two different Hebrew words and translate them both as hardening. One of these words is a "stubbornness" and the other is "courage". In plague six, God steps in and "courages" Pharaoh's heart. He does this to keep Pharaoh in the fight. Why? Because Pharaoh still hasn't changed and still values his own power. As we can see in the seventh plague, Pharaoh is once again responsible for "hardening" his own heart. At this point, God switches plans. The rest of the way (plagues 8-10 and the final scene at the Sea of Reeds), it is God doing the hardening. Prior to this, God says that his goal is that the Egyptians will know that he is God. Starting with plague 8, it turns to Moses and the Hebrew people knowing that he is God.
Even after the horrible 10th plague of the death of the firstborn, Pharaoh and his army still chase after the Hebrew slaves. Despite God's attempt to change his heart, Pharaoh isn't going to admit the obvious truth about his own power and his own gods. He had a chance and his decisions had catastrophic impacts on those who followed him. Yet, the individual households were given a chance. Any door with blood on the doorposts would be safe from the plague. And when the Israelites start their way out of Egypt, there was a "mixed multitude" to indicate that people did side with the God of Israel. Some Egyptian firstborns were saved.
Again, that doesn't necessarily make anyone feel better about innocent firstborns dying. It is something to struggle with, especially if it really happened. I can actually see love, patience, and mercy throughout this story, even for the "bad guys", but there is clearly a ton of tragedy. Deliverance for one group can be pain for another group. This is a story primarily from the perspective of the liberated. It's not a story of God just one day deciding to kill people for fun.
And that's where the even-larger story comes into play. I can easily see concluding God is a maniac from just this story. But, if one gains trust in this God from other stories, then maybe one can accept his actions in this one. Or maybe not. Despite all of this, I still struggle with it a bit. Couldn't it have happened another way?
Also, speaking from your personal perspective, how often are you looking for less obvious explanations for scripture when they align with intuitively moral practices? What would be an example of scripture that most people agree highlight moral acts by God when read literally but you feel should be interpreted in a less flattering manner?
I'm not sure I understand these questions. Something that most people think makes God look good but I think it makes God look bad? Nothing comes to mind right now, but I'll think about it.