Cris Carter -- BLASTS ADRIAN PETERSON ... How DARE YOU Beat Your Child

NFL legend Cris Carter just WENT OFF on Adrian Peterson -- scolding the Vikings running back for beating his 4-year-old kid ... and admitting his own mother was wrong for hitting him as a child.

The whole thing was incredibly emotional -- with Carter appearing on ESPN's "Sunday NFL Countdown" and ripped the idea that Peterson's form of punishment was OK because that's how AP was taught when he was a kid.

"My mom did the best job she could do ... but there are thousands of things I have learned since then -- that my mom was wrong."

"She did the best she could, but she was wrong about some of the stuff she taught me ... and I promised my kids I won't teach that mess to them."

Carter then hails the Vikings -- his former team -- saying they did the right thing by deactivating AP.