The reference in
John 20 isn't a reference to baptism. It's mirrored quite well in something Matthew wrote. Compare the two:
John 20:21-23
21Then said Jesus to them again, Peace be unto you: as my Father hath sent me, even so send I you.
22And when he had said this, he breathed on them, and saith unto them, Receive ye the Holy Ghost:
23Whose soever sins ye remit, they are remitted unto them; and whose soever sins ye retain, they are retained.
Matthew 18:15-18
15Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother.
16But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established.
17And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican.
18Verily I say unto you, Whatsoever ye shall bind on earth shall be bound in heaven: and whatsoever ye shall loose on earth shall be loosed in heaven.
Jesus is essentially referencing in
John 20 what he had taught them earlier as found in
Matthew 18. This has nothing to do with baptism.
We almost make preachers little popes. I fear we're becoming "Cathostolic".