THIS is how we are so certain we have the correct understanding, rwa265. He has ALREADY made known to us His will. It's no secret. It WAS a secret (Rom. 16:25,26) kept secret in Him since the world began, but it is NOW made manifest through the revelations that the risen Christ gave to Paul for the building of the Body of Christ. The mystery (secret) has been told to us. It's all laid out in His word. So I think the correct question would be "which part of His word is correct for the Body of Christ today?" It's not animal sacrifice, it's not baptism for the remission of sins, it's not dietary rules, it's not the law, it's not circumcision. They are all there, in His word, but they are not all for our doing. So, what is "for our doing"?
It’s always interesting when sects try to “teach” us what the “secrets” and “mysteries” of Christ really are when it’s all right there in scripture.