No, it's not because they are angry at God. If they are angry at all, it's anger at religion for promising so much and delivering so little. Rightly so, in many cases.
Why people are atheists of course is going to vary like the colors of the rainbow. If you're talking those who just didn't 'get it' growing up, that can be for many factors. Not the least of which would be the way religion is explained to them. If they are rationally oriented, telling them to set all that aside and "just believe" in what amounts in their minds to fairy tales, that's not their fault. It's just a simple mismatch of modes of thinking clashing with one another.
For others who were believers, but later found those beliefs unsatisfactory, that could be a matter of their own faith development, growing beyond mythic-literal thinking into a larger vision, but lacking any developed structures they can rationally acknowledge. Again, a lot of that failure is due to the church itself being behind modernity and stuck in a mythic-literal past.
They don't "hate God", but rather just find religion like that to be childish, and have no other place to look to other than the promise that reason and science will provide these answers where religion failed. That too exists within that spectrum of colors. It's not all just one thing, or for one reason. More reasons too could be looked at.
As above. For myself personally speaking, it was because the questions I had needed a larger container than what they offered. Denying reason and science, in order to preserve beliefs, was not faith to me. It was fear. I was and am still of the mind, that faith and reason should complement each other, not compete.
Could be what they were presented with, and how it was presented. Could be the symbolism just never spoke to them. Could be that they just have no interest in the larger questions of life, such as "why do I exist". Some people are just content living life and not trying to understand "big picture" questions like that.
That's certainly true of religious folks too, who simply never wish to try to understand beyond what they are taught in church. They're just content knowing the basic rules, and not questioning things. That's one possibility, but of course they are many others too that could be looked at.