I think too many folks here are letting Jesus off the hook too easily just by attacking his association with the Israelite god of war. He had tons of terrible teachings, even in the sermon on the mount. I find far greater fault in his actual teachings than his attempt to parlay the existing believe in yahweh into a basis for common ground for the beginning of his new religion. You'll have to forgive me as I can't be bothered to look up scriptural citations, but some issues with Jesus off the top of my head are:
Golden rule - it assumes that everyone is the same and fails to encourage putting yourself in the other person's shoes. Instead of doing to others as you'd have them do to you, treat others how they want to be treated. A fundamentalist christian might think "If I were so delusional as to think I'm gay, I'd want people to shout me down and send me to conversion therapy, etc" but I suspect most gay people don't actually want to be treated that way. You could argue that most people would want others to consider how they want to be treated, and through that extra step you can get to the better rule, but if Jesus meant that, he should've said it. Not saying it confuses the matter if that's what the true ideal is.
Those who lose brother or sister or mother or father for my name will gain those back a thousand fold. (again, I forget the exact words, but you get the gist) and I think there's one where he says if you love your family more than him you're not worthy of him...Sounds like a cult leader to me - preaching the doctrine of separating families.
Don't store up treasures on earth - store them up in heaven. The idea that life doesn't really start until the afterlife is one of the most pernicious religious doctrines that there are. It doesn't take much imagination these days to see how that teaching could go wrong.
Turn the other cheek - I wonder how many victims of domestic abuse went on living in terror due to this teaching.
He taught that the only unforgivable sin was blasphemy against the holy spirit. Really, dude? That's the one you pick to be unforgivable? I guess when you teach that this life is temporary and unimportant compared to the afterlife (see above) it doesn't really matter if people go around killing - that can be forgiven. But don't you dare think about talking shit about something that doesn't exist.
Conspicuous by it's absence in Jesus' teachings is any condemnation of slavery. While I don't think it's generally ok to condemn someone for everything they didn't say, this would've been an easy moral victory for him. He would've had plenty of exposure to slavery and it's obvious result in human suffering, but he was too much of a coward to condemn it.
But, by far, the worst thing that Jesus taught was absolutism. Anyone that didn't believe that Jesus was the shit was to be condemned. Anyone who thought that maybe his way wasn't perfect was not worthy and to be ignored and cast out. You're either with him, or against him. Black and white. Again, so many times, he sounds like a cult leader. He never acknowledged moral nuance and grey areas, he discouraged independent thought, or any attempts to develop an even better moral code than what he offered. This sort of absolutism has lead to religiously motivated genocide for most of human history. It leads to closed minds and tribalism. It leads to being stuck at a sub-optimal moral code when we have the means to develop a far better one.