Will putting moldy bread in the microwave kill the bacteria and make it safe to eat?

No you won't get high enough temperatures without ruining the bread but common bread mold isn't especially harmful, you're probably not going to die from eating mold; you'll digest it like any other food, and as long as you've got a relatively healthy immune system, the worst that might happen is when you look at it and think about what you are eating you might get a little nausea at the idea/taste. That said, this stuff is definitely not good for you, and if you're allergic to mold, it can bring on uncomfortable symptoms including irritation of the eyes, nose, and throat.