Baptism purpose ≠ Sign of the covenant.
In Rom.6:3-11, is seen the purpose for Baptism and it isn't as a sign of the covenant. Notice: "Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life. For if we have been planted together in the likeness of his death, we shall be also [in the likeness] of [his] resurrection: Knowing this, that our old man is crucified with [him], that the body of sin might be destroyed, that henceforth we should not serve sin. For he that is dead is freed from sin. Now if we be dead with Christ, we believe that we shall also live with him: Knowing that Christ being raised from the dead dieth no more; death hath no more dominion over him. For in that he died, he died unto sin once: but in that he liveth, he liveth unto God. Likewise reckon ye also yourselves to be dead indeed unto sin, but alive unto God through Jesus Christ our Lord."
Isn't what Paul is telling here the message that Jesus is telling Nicodemus??
John3:3-17,"Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God. Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother's womb, and be born? Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and [of] the Spirit, he cannot enter into the kingdom of God. That which is born of the flesh is flesh; and that which is born of the Spirit is spirit. Marvel not that I said unto thee, Ye must be born again. The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit. Nicodemus answered and said unto him, How can these things be? Jesus answered and said unto him, Art thou a master of Israel, and knowest not these things? Verily, verily, I say unto thee, We speak that we do know, and testify that we have seen; and ye receive not our witness. If I have told you earthly things, and ye believe not, how shall ye believe, if I tell you [of] heavenly things? And no man hath ascended up to heaven, but he that came down from heaven, [even] the Son of man which is in heaven. And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up: That whosoever believeth in him should not perish, but have eternal life. For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved."
Isn't that the same message seen in Titus 3:3-7, "For we ourselves also were sometimes foolish, disobedient, deceived, serving divers lusts and pleasures, living in malice and envy, hateful, [and] hating one another. But after that the kindness and love of God our Saviour toward man appeared, Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost; Which he shed on us abundantly through Jesus Christ our Saviour; That being justified by his grace, we should be made heirs according to the hope of eternal life."
"washing of regeneration"=(paliggenesia)
having these meanings: new birth; renewal; re-creation. (i.e.)a spiritual birth----As Jesus said in John 3.
1Pet.3:21 when one leaves off the () phrase shows the same thought---In Baptism--the raising up(Resurrection) of Christ assures the salvation of the Redeemed.