Working at a shelter I've seen cats with all kinds of issues. This cat may not like children and needs to be in an adult home. If the cat is attacking your son this may not be the right fit for your household. Kids are kids and of course want to play with the cat. The first thing you should do is contact the Shelter where you adopted from, if it is a good one they will help you and take back the cat and letting you adopt another more friendly family cat. Shelter's should know the cat's ability/personality to either be in an adult home, no other pets, not small children, etc.
I agree with the one poster that many people might not like my opinion on this issue, but it is one thing for adults to work with a new cat with issues, but if you cannot trust the cat to be around your son then it should not be in your home. Some animals do not like children and won't ever like children - for the safety of your son you need to take this cat back to the shelter as fast as you can before any injury to your son happens.
I agree with the one poster that many people might not like my opinion on this issue, but it is one thing for adults to work with a new cat with issues, but if you cannot trust the cat to be around your son then it should not be in your home. Some animals do not like children and won't ever like children - for the safety of your son you need to take this cat back to the shelter as fast as you can before any injury to your son happens.