Abstractions are used to aid our understanding - they are not to be taken literally. For example, no one has physically circumcized the foreskin of their heart per Deu 10:16 and Jer 4:4. You can support almost any argurment by using abstractions.
Your arguments made from Biblical abstractions conflict with the clear directives on water baptism in the Great Commission, Acts, and the Epistles.
The only conflict is in your resistance, reflecting a nominal and shallow faith. I'm trying to aid your understanding.
"When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things. For now we see through
a glass, darkly; but then face to face: now I know in part; but then shall I know even as also I am known. And now abideth faith, hope, charity, these three; but the greatest of these is charity." ( 1 Cor 13:11-13)
Notice the absence of age of consent/consciousness, permission, declaration of faith, etc. Because that is radical and unbiblical. -- Faith is from first to last (Rom 1:17), it doesn't delay or pause. That is the hiccup in your logic, hypocrisy and negligence. The earlier the better.
Baptism is
necessary for Gentiles/heathens/pagans/polytheists to "wash" away former sin (idolatry etc), as
proselytes into Israel. The early church barred people from baptism not by age but by obviously sinful practices, as charioteers, gladiators, astrologers, diviners, magicians, polygamists, etc,
unless they forsook their profession. Consent is only for this group. Cf the dialogue between the Ethiopian eunuch and Steven: "What doth hinder me to be baptized? And Philip said, If thou believest with all thine heart, thou mayest." (Acts 8:36-37)
A convert is a proselyte, a "new comer", or "to come", converting his old life into a new citizenship in the
Commonwealth of Israel, not a denomination, church, or even Christendom as
the Church, as all of that falls under the Commonwealth.
All of his family (household, business, etc) will fall under the same grace offered to him. Get it?
Like asylum seekers, Gentile salvation
partly relies on OT precedence, e.g. equivalence between Jew and Gentile once proselytised, as legal basis for citizenship. "One law and one manner shall be for you, and for the stranger that sojourneth with you." (Num 15:16) That's how there can be 'Jew and Gentile' together. Gentile theology is not superior or a replacement, but rather our covenant works
alongside theirs, as co-workers.
The problem historically was that Gentiles had a limited window, e.g. 7th year on
shmitta (year of rest), in order to claim citizenship. Until the HS made that open.
The original process was circumcision + baptism + confession:
"From the law that proselyte and native Israelite should be
treated alike (Num. xv. 14 et seq.) the inference was drawn that
circumcision, the
bath of purification, and sacrifice were prerequisites for conversion (comp. "Yad," Issure Biah, xiii. 4) ... he was
circumcised in the presence of three rabbis, and
then led to be baptized; but even while in the bath he was instructed by learned teachers in the graver and the lighter obligations which he was undertaking. After this he was considered a Jew (
Yeb. 47a, b). ... Instruction in the Jewish religion precedes the ceremony, which, after
circumcision and baptism, consists in a
public confession of faith, in the main amounting to a repudiation of certain Christian dogmas, and concluding with the
reciting of the Shema'."
PROSELYTE - JewishEncyclopedia.com
Yes, most certainly there is a parallel to circumcision. And the parallel remains although the Apostolic Council exempted Gentiles from circumcision, as 'generation' from the flesh is redundant to '
re-generation', that is of the heart per the HS. The fleshly token is meaningless to a spiritual people, born not by genetics from Jacob, but as
goyim chosen by the HS. So our token or rite is spiritual. Hence "circumcision is of the heart" not flesh. The "heart" represent our mind and thoughts (Mt 15:8).
"This people draweth nigh unto me with their mouth, and honoureth me with their lips; but
their heart is far from me." (Mt 15:8; Isa 29:13; Ezek 33:31; Acts 8:21; Heb 3:12)
This metaphor is a critical as Gentiles are
not supernaturally born per God's promise to Abraham relating to Isaac and Jacob. But rather our 'flesh is weak' because we are 'unclean', filthy in thought and deed, so our life starts as dirt, useless and unclean.
So we washing away our filth, in response to God's grace, who has chosen to remake what is originally worthless anew in the image of Christ. Wild (frail) branches "cut out of the olive tree which is wild by nature" (Rom 11:24) implanted for repair in the "root and fatness of the olive tree" (Rom 11:17) that is Christ. Farmers graft to save the root/tree (from disease etc) but God grafts to save the person/family/nation/kingdom. "Whosoever is called".
To allege that that is a "biblical abstraction" would be 100% correct.
Baptism is purification
and importation as a person is baptised
into Christ (Rom 6:3-4, Gal 3:27; εἰς Χριστὸν Ἰησοῦν εἰς τὸν θάνατον), both life
and death. "This formula appears in other connections, as, for example, "baptised into Moses" (I Cor. 10:2) and "baptised into the name of Paul" (I Cor. 1:13)." (see John Murray on Baptism, 'For you and Your Children', pp 108-109,
https://faculty.wts.edu/wp-content/uploads/2017/06/For-You-And-Your-Children.pdf; also pp 113 on the semantics of βαπτίζω (baptizo) with Isa 21:4, 2 Ki 5:14, Ps 68:23, Lev 11:32)
"This is the covenant that I will make with them after those days, saith the Lord,
I will put my laws into their hearts, and in their minds will I write them; And their sins and iniquities will I remember no more." (Heb 10:16-17)
We wash with water AND with blood in response to "Him that loved us, and washed us from our sins in his own blood" (Rev 1:5)
And per the promise to Abraham, "it shall be a token of the covenant betwixt me and you. And he that is eight days old shall be circumcised among you,
every man child in your generations, he that is born in the house, or bought with money of any stranger, which is
not of thy seed." (Gen 17:10-12)
That is the relevance and parallel.
The
object however is
into the Triune God, more than "in the name of the Lord Jesus" (Acts 8:16) The Lord's expressed words pre-ascension: "baptizing them in the name of the Father, and of the Son, and of the Holy Ghost" (Matthew 28:19). i.e. "A cord of three strands is not easily broken" (Ecc 4:12) A triply strong graft. That's the similarity and the difference to earlier baptisms.
Whether this is all metaphorical or all literal is uncertain, but per literalisms like new "rivers" prophesied in Jerusalem in Ezek 47:1-5, and everything we know about the new kingdom, it very well may be super literal even though now that may seem abstract and difficult to grasp.