What does it mean to believe and be a Christian? The first part

What does it mean to believe and be a Christian?

In the Gospel of John 1:12 it is written as follows:
And as for those who accepted him, he gave power to become the children of God, that is, to those who believed in his name, he gave power to become the children of God.
John says in this section that this is the closest possible to an intimate relationship of love. Sometimes in the New Testament, this love is compared to a husband and wife. This relationship is so close and intimate.
If you are married, you know you are married, so if you are a Christian, know for sure that you are a Christian. God wants you to be sure of this.
In 1 John 5:13, John wrote: I have written this to you who have believed in the name of the Son of God, so that you may know that you have eternal life and that you may believe in the name of the Son of God.
You can be sure that you are a Christian. You can be sure that you are in this relationship and you can be sure that you have eternal life. What is the basis of such faith and belief? This is a step of faith based on evidence. It is based on facts, not feelings.
If you ask someone you are married to provide a witness to prove that he is married, the best witness is the marriage certificate. Along with the love that is in this relationship, this document proves it.
If a Christian wants to prove that he is a Christian, the evidence is the Bible, the word of God. Our understanding of God is based on God’s promises.
In Romans 10:17, Paul says: Faith comes from hearing and hearing from the word of God.
The Bible is the way we interact with God, so you can start reading and doing it.
For example, one of the promises that Jesus Christ gave in verse 20 of chapter 3 in Revelation is that I am standing at the door and knocking, if anyone hears my voice and opens the door, I will come to him and have dinner with him. ate and he also with me.