Born again
Jesus answered, “Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. (John 3:5)

Baptism unto repentance
There are 2 baptisms that we are to obey one of baptism of water which is unto repentance and the other of the Spirit which is unto transformation or renewal. Baptism of water is by man (usually the pastor or spiritual oversight), but the baptism of the Holy Spirit is by the Lord Himself. Water baptism is baptism unto repentance which is to ‘change or reverse’ our decision, from one of sin, world and the devil to one of following Christ in righteousness (right conduct towards God and man)

Baptism unto renewal/transformation
I indeed baptize you with water unto repentance, but He who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and fire. (Mat 3:11)

The baptism of the Holy Spirit is one that renews us. The Lord will baptize us and we will begin on the journey of being cleansed internally. Cleansed internally permanently change our decision as well as our status to be children of God. Fire makes permanent changes, even as it purifies (Prov 17:3)

that He might sanctify and cleanse her with the washing of water by the word (Eph 5:26)

We begin the journey of our cleansing internally by the Word of God, if we allow the power of the Word to renew us. Repentance means we decide to stop sinning and follow Jesus, to be renewed means allowing the Lord, through His Word to renew us to seal our decision in following Christ. By our decision alone we cannot be saved, we need to be renewed inside otherwise our salvation is not complete and cannot sustain until Jesus takes us home or when He returns.

And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God. (Rom 12:2)

Our decision to follow Jesus means that we cannot conform to the old life of sin and the world anymore but conform to Christ, but we need to be transformed to know God’s good, acceptable and perfect will. We leave ‘self’ will and go into God’s will, we no longer live for ourselves but live for Christ (Gal 2:20). That is the reason why our born again doesn’t start at the birth of Jesus but rather at the cross. Died to old that the new may live.

not by works of righteousness which we have done, but according to His mercy He saved us, through the washing of regeneration and renewing of the Holy Spirit, (Tit 3:5)
For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, (Eph 2:8)

We must be continually thankful for our salvation and know that it is God’s work of salvation; otherwise we might end up in pride and self-righteousness

New life after baptism
Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new. (2Co 5:17)

New creation means our old life is passed away (died) and our life is new (born again)

Or do you not know that as many of us as were baptized into Christ Jesus were baptized into His death? Therefore we were buried with Him through baptism into death, that just as Christ was raised from the dead by the glory of the Father, even so we also should walk in newness of life.. (Rom 6:3-4)

Our water baptism is likening to death unto resurrection. We died to our self and sin but now live to God and this life glorifies God. The other way of looking at this is that without the death (of the old life), there is no resurrection.

Important proofs of a new life
1. Humility, meekness, patience and in love
I, therefore, the prisoner of the Lord, beseech you to walk worthy of the calling with which you were called, with all lowliness and gentleness, with longsuffering, bearing with one another in love, (Eph 4:1-2)
2. Being truthful in speech
but, speaking the truth in love, may grow up in all things into Him who is the head—Christ— (Eph 4:15)
3. Not living in vanity or futility, meaning to be morally pure not ‘heathenistic’ in our life, that is to live as though there isn’t a moral God watching (Eph 5:3-5).
This I say, therefore, and testify in the Lord, that you should no longer walk as the rest of the Gentiles walk, in the futility of their mind, (Eph 4:17)
4. Controlled emotions
“Be angry, and do not sin”: do not let the sun go down on your wrath, nor give place to the devil. (Eph 4:26-27)
5. Don’t steal and work honestly (Eph 6:5-7)
Let him who stole steal no longer, but rather let him labor, working with his hands what is good, that he may have something to give him who has need. (Eph 4:28)
6. Treat each other with love (also Eph 5:2, 21)
Let all bitterness, wrath, anger, clamor, and evil speaking be put away from you, with all malice. And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you.. (Eph 4:31-32)
7. Don’t thrive in excesses but ready to bless others
And do not be drunk with wine, in which is dissipation; but be filled with the Spirit, speaking to one another in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord, (Eph 5:18-19)
8. Obedience to parents and honor them
Children, obey your parents in the Lord, for this is right. “Honor your father and mother,” which is the first commandment with promise: (Eph 6:1-2)
9. Biblical husband and wife relationship
Wives, submit to your own husbands, as to the Lord…. Husbands, love your wives, just as Christ also loved the church and gave Himself for her, (Eph 5:22, 25)
10. Father and children relationship. Our training and admonishment has to be Biblically based not humanistic. We plumb line has to from the Bible, therefore to fathers need to be grounded in the Word in order to train and admonish appropriately.
And you, fathers, do not provoke your children to wrath, but bring them up in the training and admonition of the Lord. (Eph 6:4)

Jesus told Nicodemus that the way into Kingdom of God is by the baptism of water and the Spirit. It is not ‘pick-and-choose’ or optional. Baptism unto repentance is the start of our journey of the baptism of Fire that metamorphosis our life permanently into a child of God. He doesn’t just merely want to ‘save’ us but also want to harvest fruit of righteousness (Phil 1:11).