The Bible says,

The Spirit Himself bears witness with our spirit that we are children of God.

Romans 8:16 - NKJV

As long as you are not blocking it out, the Spirit of God is providing you with an inner assurance that you have indeed been born again. The Holy Spirit has a relationship with you at the level of your spirit and from there is testifying to you of your newly given sonship. The sense of this sonship will be constantly coming up into your consciousness from your spirit. Nevertheless, it may well be though that you have yet to truly comprehend the meaning of this message you are receiving from within you.

In order to come to a full comprehension of what has happened, in order to be established in what has taken place, you need more than the inner witness provided by the Spirit. You also need God's Word to declare it to you.

For this purpose you need to look in the Bible at God's promises about your sonship. Your inner witness needs to be confirmed by a genuine source of spiritual authority and the Bible is the highest source of spiritual authority. The Bible's declarations will start to establish you in the truth of who you now are in Christ.

The Bible declares that you, as someone who has received Jesus, are born of God - it tells you you are now a child of God.

To as many as did receive and welcome Him, He gave the authority (power, privilege, right) to become the children of God, that is, to those who believe in (adhere to, trust in, and rely on) His name.

John 1:12 - The Amplified Bible

Let me put it very simply in summary form. In receiving Jesus you received life - the life of God. Then the glorious power of the Holy Spirit came over your spirit and you became God's child. I'll explain this in more detail for you in the next part of this class.