As I see it from scripture, Jesus had to suffer and die for us to appease the wrath of God against us because of our sins.
In John 3:36 we see that the wrath of God abides on all people who are sinful and who refuse to believe in Him. But when we repent of our sins and believe Jesus, His blood cleanses us from all sin and unrighteousness, and Christ becomes our advocate with the Father. Just as a lawyer pleads with the judge not to pass judgment on his client, so Jesus as our advocate stands forever pleading for us not to punish us for sin. The case Jesus makes for us (for those who believe) with His Father is this: that He has paid the penalty for our sins with His blood; and we have accepted that payment.
Thus, when God the Father see’s the precious blood of His Son that was shed for us, and that we have accepted that payment, His wrath against us is satisfied and we are forgiven (from 1 John 2:1-2).
If you are not sure that you are a Christian and that your sins are forgiven, but you want to believe, you can confess your sins to God now, and He will save you. Here is a suggested prayer:
Lord, I know I am a sinner. I realize that I am under judgment and your wrath is against me. I believe Jesus died for me to save me from the penalty of my sin. I accept His love for me and payment for my sins. Please, Lord, save me now and accept me into Your forever family. Help me to live for You as you want me to live. Amen.