The Second Birth is a miracle wrought in our hearts by the Holy Spirit. It is hands down the most important thing ever in your life.
It is about Jesus being formed inside of you in a mysterious yet tangible way. It is a process and continues day by day until Jesus returns.
Jesus said You must be Born Again, and that it is like the wind blowing, a mystery, not predictable as we would wish.
The Roman Catholics say:"If you are infant baptized you are surely born again"
The Evangelicals says:"If you are adult baptized you are surely born again"
The Charismatics say:"If you respond to the altar call you are surely born again"
Jesus said it is a mystery and it is like the wind. The Bible as a whole teaches that the Holy Spirit must form Christ inside you, by the preaching of the Word and this is a process and a mystery.
3 Jesus answered and said to him, “Most assuredly, I say to you, unless one is born again, he cannot see the kingdom of God.”
4 Nicodemus said to Him, “How can a man be born when he is old? Can he enter a second time into his mother’s womb and be born?”
5 Jesus answered, “Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God.
6 “That which is born of the flesh is flesh, and that which is born of the Spirit is spirit.
7 “Do not marvel that I said to you, ‘You must be born again.’
8 “The wind blows where it wishes, and you hear the sound of it, but cannot tell where it comes from and where it goes. So is everyone who is born of the Spirit.”
John 3:3-8
This is a precious process and takes time. We will indeed be "once saved always saved" as soon as you are fully saved. You are being saved IF you are working with the Holy Spirit day by day. Just like the parable of the sower it is a slow process just like farming.
1 Peter, an apostle of Jesus Christ, To the pilgrims of the Dispersion in Pontus, Galatia, Cappadocia, Asia, and Bithynia,
2 elect according to the foreknowledge of God the Father, in sanctification of the Spirit, for obedience and sprinkling of the blood of Jesus Christ: Grace to you and peace be multiplied.
3 Blessed be the God and Father of our Lord Jesus Christ, who according to His abundant mercy has begotten us again to a living hope through the resurrection of Jesus Christ from the dead,
4 to an inheritance incorruptible and undefiled and that does not fade away, reserved in heaven for you,
5 who are kept by the power of God through faith for salvation ready to be revealed in the last time.
6 In this you greatly rejoice, though now for a little while, if need be, you have been grieved by various trials,
7 that the genuineness of your faith, being much more precious than gold that perishes, though it is tested by fire, may be found to praise, honor, and glory at the revelation of Jesus Christ,
8 whom having not seen you love. Though now you do not see Him, yet believing, you rejoice with joy inexpressible and full of glory,
9 receiving the end of your faith—the salvation of your souls.
10 Of this salvation the prophets have inquired and searched carefully, who prophesied of the grace that would come to you,
11 searching what, or what manner of time, the Spirit of Christ who was in them was indicating when He testified beforehand the sufferings of Christ and the glories that would follow.
12 To them it was revealed that, not to themselves, but to us they were ministering the things which now have been reported to you through those who have preached the gospel to you by the Holy Spirit sent from heaven—things which angels desire to look into.
13 Therefore gird up the loins of your mind, be sober, and rest your hope fully upon the grace that is to be brought to you at the revelation of Jesus Christ;
14 as obedient children, not conforming yourselves to the former lusts, as in your ignorance;
15 but as He who called you is holy, you also be holy in all your conduct,
16 because it is written, “Be holy, for I am holy.”
17 And if you call on the Father, who without partiality judges according to each one’s work, conduct yourselves throughout the time of your stay here in fear;
18 knowing that you were not redeemed with corruptible things, like silver or gold, from your aimless conduct received by tradition from your fathers,
19 but with the precious blood of Christ, as of a lamb without blemish and without spot.
20 He indeed was foreordained before the foundation of the world, but was manifest in these last times for you
21 who through Him believe in God, who raised Him from the dead and gave Him glory, so that your faith and hope are in God.
22 Since you have purified your souls in obeying the truth through the Spirit in sincere love of the brethren, love one another fervently with a pure heart,
23 having been born again, not of corruptible seed but incorruptible, through the word of God which lives and abides forever,
24 because “All flesh is as grass, And all the glory of man as the flower of the grass. The grass withers, And its flower falls away,
25 But the word of the Lord endures forever.” Now this is the word which by the gospel was preached to you.
1 Peter 1
I pray the Lord work this in each of us, fully, until that day!
Even so come, Lord Jesus!