The answer is yes, we can know that we have been born again, or born from above, (as the passage might be better translated).
In his first letter, the apostle John gives us several marks or effects of the new birth by which it can be known. Let’s look at what he has to say.
The first mark of being born from above is found in 1 John 2:29, “If you know that he is righteous, you may be sure that everyone who practices righteousness has been born of God.”
John points this out because there are many who, as Paul says, “profess to know God, but by their deeds deny him” (Tit. 1:16). They say that they are Christians, but they practice unrighteousness. John says, “No, those who have been born of God practice righteousness.” That is, their lives may be characterized by this. They live in obedience to God’s commands.
The second mark is closely related to this. It is found in 1 John 3:9, “No one born of God makes a practice of sinning, for God’s seed abides in him, and he cannot keep on sinning because he has been born of God.”
He is not suggesting that a true Christian lives in sinless perfection, but that the life of a true Christian cannot be characterized as a life of disregard for God and his commandments. A true Christian, one who has been born of God (or born from above) does not make a practice of sinning. And the reason he doesn’t make a practice of sinning is because he has something of the divine nature imparted to him: “God’s seed abides in him.” A man’s son bears the characteristics of his father. You often detect a strong physical resemblance between father and son. Their mannerisms, too, are often similar. The way they speak is similar. So is the way they react to things. Why the similarity? Because the son is the son of his father. In the same way, those who are born of God share in the holiness of God. If you find someone who professes to know God but they seem to have no concern to grow in holiness, you have found someone who is deceived.
The third mark of being born from above is found in 1 John 3:14, “We know that we have passed out of death into life, because we love the brothers.”
This thought is repeated a little later when he says, “everyone who loves the Father loves whoever has been born of him” (1 John 5:1a). So do you love the saints? Do you love God’s people? Do you prefer the company of Christians to the company of unbelievers? If so, you have one of the marks being born of God.
The fourth mark is found in 1 John 5:1b, “Everyone who believes that Jesus is the Christ has been born of God.” In other words, if you acknowledge Jesus of Nazareth to be the promised Messiah, which is the same thing that Paul says in Romans: “If you confess with your mouth that Jesus is Lord” (Rom. 10:9) — and this is a sincere confession from the heart—then you have a mark of having been born of God (cf. 1 Cor. 12:3).
The fifth mark of being born from above is found in 1 John 5:4, “For everyone who is born of God overcomes the world.” This means that no one who is born of God is continually ensnared by the world. Earlier in the letter he had said,
“Love not the world or the things in the world. If anyone loves the world, the love of the Father is not in him. For all that is in the world—the desires of the flesh and the desires of the eyes and pride in possessions—is not from the Father but is from the world” (1 Jn. 2:15-16).If we are continually overcome by the desires of the flesh (see Gal. 5:16ff), or find that the fundamental motivating force in our thinking is the acquisition of wealth, and the things that wealth can buy, then we love the world and the love of the Father is not in us. But if we find that in fact we are overcoming the world; if we find that these things do not have a powerful hold over us; that we are motivated instead by a love for God and a love for our neighbor; then we have another mark of having been born of God.
Near the end of his letter John says,
I write these things to you who believe in the name of the Son of God that you may know that you have eternal life (1 Jn. 5:13).And if these things are so, we may, as Paul says in Romans, “draw near [to God] with a true heart in full assurance of faith” (Heb. 10:22).