It is just what everyone has been telling you, the water baptism is the outward sign of the inner repentance from doing bad deeds.
What about what the scriptures have been telling us?
Mark 1:1-5---King James Version
1
The beginning of the gospel of Jesus Christ, the Son of God;
2 As it is written in the prophets, Behold, I send my messenger before thy face, which shall prepare thy way before thee.
3 The voice of one crying in the wilderness, Prepare ye the way of the Lord, make his paths straight.
4 John did baptize in the wilderness,
and preach the baptism of repentance for the remission of sins.
5 And there went out unto him all the land of Judaea, and they of Jerusalem, and were all baptized of him in the river of Jordan, confessing their sins.
Acts 2:38---King James Version
38 Then Peter said unto them,
Repent, and be baptized every one of you in the name of Jesus Christ
for the remission of sins, and ye shall receive the gift of the Holy Ghost.
Acts 22:16---King James Version
16 And now why tarriest thou? arise, and
be baptized, and wash away thy sins, calling on the name of the Lord.
The scriptures testify repentance and water baptism was for God's grace of the remission of sins.
The Good News is NOT that we can be dunked under water but that we can have a change of heart.
We can experience both. One does not preclude the other.
And it is the inner change that is pleasing to God. Water has zero efficacy towards salvation.
That isn't the testimony of the Savior:
Mark 16:16---King James Version
16
He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
You cannot take one verse out of context and build a whole theological system out of it as you have done. If John did require people to be baptized then Paul qualifies that as an outward sign of the inner transformation. IOW there are more details or explanations that fill in the gaps of why specific people did the things they did.
Why do the verses above amount to a single verse?
And why does your theology take zero verses and build a "theological system" out of it ---somehow cover up or cancel out the Biblical testimony found in the posted scriptures above?
You are aware the Early Church Fathers, for centuries--believed water baptism was connected to being born again--and no man could enter into heaven without it--if they had reached an age of accountability?
ST. JUSTIN MARTYR (inter A.D. 148-155)
Whoever is convinced and believes that what they are taught and told by us is the truth, and professes to be able to live accordingly, is instructed to pray and to beseech God in fasting for the remission of their former sins, while we pray and fast with them.
Then they are led by us to a place where there is water; and there they are reborn in the same kind of rebirth in which we ourselves were reborn: In the name of God, the Lord and Father of all, and of our Savior Jesus Christ, and of the Holy Spirit, they receive the washing with water. For Christ said,
"Unless you be reborn, you shall not enter into the kingdom of heaven." ...The reason for doing this, we have learned from the Apostles. (The First Apology 61)
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ST. IRENAEUS (c. A.D. 190)
"And [Naaman] dipped himself...seven times in the Jordan" [2 Kings 5:14]. It was not for nothing that Naaman of old, when suffering from leprosy, was purified upon his being baptized, but [this served] as an indication to us. For as we are lepers in sin, we are made clean,
by means of the sacred water and the invocation of the Lord, from our old transgressions, being spiritually regenerated as new-born babes, even as the Lord has declared: "Except a man be born again through water and the Spirit, he shall not enter into the kingdom of heaven." (Fragment 34)
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TERTULLIAN (inter A.D. 200-206)
A treatise on our sacrament of water, by which the sins of our earlier blindness are washed away and we are released for eternal life will not be superfluous.....taking away death by the washing away of sins. The guilt being removed, the penalty, of course, is also removed.....Baptism is itself a corporal act
by which we are plunged in water, while its effect is spiritual, in that we are freed from sins. (On Baptism 1:1; 5:6; 7:2)
..
.no one can attain salvation without Baptism, especially in view of the declaration of the Lord, who says:
"Unless a man shall be born of water, he shall not have life." (On Baptism 12:1)
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RECOGNITIONS OF CLEMENT (c. A.D. 221)
But you will perhaps say,
"What does the baptism of water contribute toward the worship of God?" In the first place, because that which has pleased God is fulfilled. In the second place, because when you are regenerated and born again of water and of God, the frailty of your former birth, which you have through men, is cut off, and so ...you shall be able to attain salvation; but otherwise it is impossible. For thus has the true Prophet [Jesus] testified to us with an oath:
"Verily, I say to you, that unless a man is born again of water....he shall not enter into the kingdom of heaven." (Recognitions 6:9)