58 minutes is lots of time at ATL. Someone will no doubt tell you that it won't be if you are late getting there. No time is safe if you are late and you are just as likely to be early as late. I think, but couldn't find at delta.com, the official "minimum connection time" at ATL is 35 minutes. I have done it in a lot less. I am a bit confused to know whether this is all on one ticket or not. If not, it would take a few extra minutes to checkin in ATL.
Also, FYI, there is loads of award availability SAT-EWR on Dec. 30 in First.