You .................. need........................ to ........... understand ............ who is ........... talking !!
AND TO WHOM ????? ???? ??? ??? ???
'All nations' is pretty clear to me (Matthew 28:19-20 NASB).
Even if water baptism was a relic of the old covenant (which it is not), it isn't unnecessary except
for the express purpose of being justified by it. But it's also true that EVERYTHING a person does (besides believing) is unnecessary to be justified (made righteous in God's sight). Including 'love your neighbor as yourself', because the only thing that justifies is the forgiveness of God received as a free gift through believing in that free gift.
So, everything else we are commanded to do, now that we are justified through faith in the blood, is simply the expected and obligatory show of that faith. Like the servant in Matthew 18:23-35 who was forgiven his debt. The expectation was that, now that he was forgiven his debt, he would act in a manner
consistent with the grace he had received. That's what obedience in the Christian faith is all about (Titus 2:11-13 NASB).
'I don't have to' seems to be the mantra of the present Protestant Church (generally speaking, of course). She (the church) is oblivious to the fact that what
'I don't have to' means is you don't have to do anything (besides believe)
to earn justification. But we have lots of things commanded of us that we 'have' to do because they are the actions commensurate with someone who has repented and has received the forgiveness of sin through the blood of Christ and has been set free from wickedness (Acts 26:20 NASB).
Simply put, not getting water baptized can potentially be the evidence that a person has not believed in Christ to the point of affecting a born again experience. Thus the point of Jesus' statement, “He who has believed
and has been baptized shall be saved" (Mark 16:16 NASB italics mine). The person who can't, or won't, demonstrate his faith in God by his obedience to be water baptized may not be doing so because he does not truly have the new life of the believer through faith in Christ. They lack the expected outward evidence of genuine change that faith in Christ affects--
obedience to the righteous commands of Christ. John put it this way:
"anyone who does not practice righteousness is not of God" (1 John 3:10 NASB)