First being a Christian isn't about just believing certain beliefs. It's about actually coming into relationship with God. Now it is also yes about understanding certain things and agreeing to them but one can do that and never receive eternal life. John 1:12 states, "But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name..."
Here's the simple process.
Rom 10:9-10..............“The word is near you, in your mouth and in your heart” (that is, the word of faith which we preach): that if you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved. For with the heart one believes unto righteousness, and with the mouth confession is made unto salvation."
You hear the good news that Jesus died as your substitute. Rom 10:14 Some call it the Great Exchange...He took our death and gave us his life. (tasted death Heb 2:9) He took our sins and gave us his righteousness. He took our sorrows and gave us his joy. He took our griefs and gave us his peace. Isaiah 53:4 You hear that and you confess the Lordship of Christ in other words you identify and agree with him on what he said he did for you.
Sadly people get confused on just what New Covenant repentance for the sinner is. It is not repentance from sin, that is in the way that some think about it. Repentance simply means turn around, that is from having one lord, Satan and being a part of the Kingdom of darkness to embracing a new Lord....The Lord Jesus Christ. You embrace Jesus by agreeing with him by your spoken words. "For by thy words thou shalt be justified, and by thy words thou shalt be condemned."
Confession is made unto salvation. Let me illustrate things that are made unto something. Money is used unto the embracing and owning products that you buy. Or your vote is made unto you're making a reality someone to be the leader of a kingdom. Jesus said by your words you are justified or by your words you're condemned. Matt 12:37
So agree with him in what he said he did for you on the cross. And agree with him in what he said about the resurrection in that when he died...your old man sinful nature died.....and when Jesus arose from the dead.....you did as well. A part of that agreement includes the blood of Jesus which remits your sins or having them blotted out.
In the time of the Old Testament which includes Jesus time in the gospels men sought forgiveness of sins. Their sins could be pardoned and covered but they weren't blotted out until Jesus arose from the dead. Our sins if we confess and identify with Christ today are not merely covered...they're blotted out and we've been made the very righteousness of God in Christ. Not in ourselves but In Christ.
But by our coming into agreement with him with our words of agreement those words define our position in the realm of the spirit. So New Testament repentance is really doing an about face on who OUR Lord is. Put the focus on the Lordship and not how you're thinking about the deeds of sin. Deeds of sins are blotted out upon your declaring the Lordship of Christ. That's not to say once you've received LIFE, eternal life JESUS, you don't now sanctify yourself by overcoming sin....but you do that now by the life and power of God in you. Overcoming sin now isn't to get you saved. You already are. But it's about working out the salvation you've received.
"I am the vine and you are the branches. The one who remains in Me, and I in him, will bear much fruit. For apart from Me you can do nothing." John 15:5