Oz was kept in about a 5x8 ft pen for most of his first year.
That could explain the agressive traits. Dogs do need to be socialized at a young age. They also need to be crate trained, problem is, too many people use the crate (or pen or chain) as a punishment instead of a reward.
Oz is alot more leary of men than women.
Something tells me that Oz probably didn't have good experiences with men while he was in his pen.
Hard part in dealing with animals whose past are not completely known is what stimulous can trigger their agressive behavior (something as simple as a man wearing a baseball cap, because it was a man wearing a baseball cap that use to beat the dog). The other problem is some people who want to get rid of their pet may not be telling the truth as to how they tried to "train" the dog.
Brutus my "trustworthy" dog is neutered and Oz the one in question is not.
If the dog is to stay, he should be neutered.
It sounds like nothing that anyone says will convince your wife that the dog has to go so you must figure out how to keep the dog away from the baby, neuter it, and read some dog training books
+ 1 on the training books.
IMHO the real value a dog adds to home protection is his ability to wake me when something unusual happens at night. I want my labs to bark at strange people and strange noises.
+ 1
Young dogs that show agressive behavior can be trained, but it can take hard work and most likely will not happen overnight.
If you don't have the time nor propper training, you need to remove the dog from your home. I'd suggest a boxer rescue organization, but chances are they are filled to capacity. Don't just dump the dog on someone else who may not have the time as well. If the dog must be put down, make it as humane as possible, and if you truely care for the dog, take it to a vet to be put down so you can at least spend some time with him in his last moments.
Another sad reality I have learned in life is that dogs are a lot like children (don't jump on me LMTC

). They can have heartbreaking stories and you can try to help them all, but the reality is that they all can't be saved from their past.
Then again, sometimes you just have plain mean people, just like dogs.