Matthew 3:15 And Jesus answering said unto him, Suffer it to be so now: for thus it becometh us to fulfil all righteousness. Then he suffered him.
Baptism by immersion in water is the act of faith required by God for those who believe the gospel want remission of their sins.
Jesus had no sin and yet insisted on being baptised because God requires this act of faith of all who would follow him.
He submitted to baptism to set an example to his followers.
So we read:
Luke 7:30 But the Pharisees and lawyers rejected the counsel of God against themselves, being not baptized of him.
John 4:1 When therefore the Lord knew how the Pharisees had heard that Jesus made and baptized more disciples than John,
Matthew 28:19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit:
Mark 16:16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
Acts 2:38 Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins…
Acts 2:41 Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls.
Acts 8:12 But when they believed Philip preaching the things concerning the kingdom of God, and the name of Jesus Christ, they were baptized, both men and women.
Acts 8:13 Then Simon himself believed also: and when he was baptized, he continued with Philip, and wondered, beholding the miracles and signs which were done.
Acts 8:16 (For as yet he was fallen upon none of them: only they were baptized in the name of the Lord Jesus.)
Acts 8:36 And as they went on their way, they came unto a certain water: and the eunuch said, See, here is water; what doth hinder me to be baptized?... 38 And he commanded the chariot to stand still: and they went down both into the water, both Philip and the eunuch; and he baptized him.
Acts 9:18 And immediately there fell from his eyes as it had been scales: and he received sight forthwith, and arose, and was baptized.
Acts 10:47 Can any man forbid water, that these should not be baptized, which have received the Holy Spirit as well as we?
Acts 10:48 And he commanded them to be baptized in the name of the Lord. Then prayed they him to tarry certain days.
Acts 16:15 And when she was baptized, and her household, she besought us, saying, If ye have judged me to be faithful to the Lord, come into my house, and abide there. And she constrained us.
Acts 16:33 And he took them the same hour of the night, and washed their stripes; and was baptized, he and all his, straightway.
Acts 18:8 And Crispus, the chief ruler of the synagogue, believed on the Lord with all his house; and many of the Corinthians hearing believed, and were baptized.
Acts 19:5 When they heard this, they were baptized in the name of the Lord Jesus.
Acts 22:16 And now why tarriest thou? arise, and be baptized, and wash away thy sins, calling on the name of the Lord.
Baptism by immersion in water is a commandment of God to be submitted to as part of the faith which will be accounted for righteousness.
But from Paul we are given to understand that it also represents the death of our previous sinful way of life in a figure of our ‘old man’ being dead and placed in the grave. Rising up out of the water is likened to the birth of the 'new man' and the beginning of a new life lived by the commandments of God given through Jesus Christ.
Romans 6:3 Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? 4 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. 5 For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection: 6 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. 7 For he that is dead is freed from sin. 8 Now if we be dead with Christ, we believe that we shall also live with him: 9 Knowing that Christ being raised from the dead dieth no more; death hath no more dominion over him. 10 For in that he died, he died unto sin once: but in that he liveth, he liveth unto God. 11 Likewise reckon ye also yourselves to be dead indeed unto sin, but alive unto God through Jesus Christ our Lord.
By belief of the gospel and immersion in water we go from being ‘in Adam’ to being ‘in Christ’ and become heirs of the promise made to Abraham because of his faith.
Galatians 3:27 For as many of you as have been baptized into Christ have put on Christ. 28 There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. 29 And if ye be Christ’s, then are ye Abraham’s seed, and heirs according to the promise.
Righteousness will be imputed to us by our faith.
Romans 4:13 For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith. 14 For if they which are of the law be heirs, faith is made void, and the promise made of none effect: 15 Because the law worketh wrath: for where no law is, there is no transgression. 16 Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all, 17 (As it is written, I have made thee a father of many nations,) before him whom he believed, even God, who quickeneth the dead, and calleth those things which be not as though they were. 18 Who against hope believed in hope, that he might become the father of many nations, according to that which was spoken, So shall thy seed be. 19 And being not weak in faith, he considered not his own body now dead, when he was about an hundred years old, neither yet the deadness of Sara’s womb: 20 He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God; 21 And being fully persuaded that, what he had promised, he was able also to perform. 22 And therefore it was imputed to him for righteousness. 23 Now it was not written for his sake alone, that it was imputed to him; 24 But for us also, to whom it shall be imputed, if we believe on him that raised up Jesus our Lord from the dead; 25 Who was delivered for our offences, and was raised again for our justification.
The first act of faith is submission to baptism.
Thus it becometh us to fulfil all righteousness.
Without baptism we cannot begin to live by the faith which will be accounted for righteousness.
I hope you find this helpful.