Because Jesus fulfilled all the requirements of the Law he had no taint of sin for which he needed to atone. In this way he was spotless and unblemished, hence why the New Testament writers pick up the language of him as the Lamb of God, an object of sacrifice. He lived in such a way to prepare himself to be the atoning sacrifice for sin because it was the plan of God for him to do so. It was part of the redemptive plan that had been conceived in the mind of God before the world was formed. Your statement that "[h]e was perfect because he could be perfect, he is God after all," moves into the realm of the hypothetical: could Jesus have sinned? This question is not resolvable except to say that Jesus was, in fact, tempted to sin but did not.

To the extent that he loosed the chains of sin those who are his no longer face the condemnation of sin. His righteousness had been imputed to all who believe and so they no longer stand as those condemned but those redeemed. They are freed from the eternal penalty, although not the temporal penalties and effects of sin.

The Bible teaches that without the shedding of blood there is no remission of sin and in the later Old Testament prophets it is seen that the blood of animals are not fully sufficient. The entire testimony of scripture is that God purposed to use the willing sacrifice of Jesus to accomplish his purpose in redemption. Whether God could have chosen another method is irrelevant and idle speculation. God chose to work through the life, death and resurrection of Christ to accomplish his redemptive plan. Speculation about alternative plans are not helpful because they do not exist.

As I stated, we are freed from sin's condemnation. The removal of the penalty is a sign that we have been loosed from the dominion of sin since we are no longer subject to the Law's righteous consequences of sin (eternally). Also, through the regeneration of the believer's heart we begin to be conformed in this life to the likeness of Christ. This conformity will only be fully realized in glory when our entire flesh will be remade without the taint of sin. But we have the Holy Spirit who leads us to no desire sin as we did prior to our regeneration. The believer now lives, by the aid of the Holy Spirit to glorify and serve God and to put to death their sinful nature.

The unregenerate man may believe facts about Jesus but will fail to submit to him as Lord. It is necessary that all men believe in the sinless life of Jesus, his sacrificial atoning death and his bodily resurrection in order that they might be saved. Consummate with such belief they are called to follow in obedience to the commands of Christ in Baptism, the Lord's Supper and unity with the Body of Christ, the Church. God's grace causes men to believe and to repent, the Holy Spirit is a means of this grace. The grace of God and the works of the Holy Spirit are the effective causes of our belief and obedience. Jesus work was his perfect life, being for us that believe what Adam was not, the perfect head, this is why Romans picks up the theme of Jesus as the second Adam. Jesus work also included his sacrificial death which paid the price for the sins of those who would believe and his resurrection was also part of his work to show that all he had done had been successful since he conquered sin and death itself as first fruits of the resurrection that will come to all who believe.

The Gospel is not simple, the way of salvation is not simple. It is not something that requires full cognitive understanding but there are elements that do not make sense apart from the illumination that only the Holy Spirit can provide. My counsel would be to seek God in the scriptures, to read about the work of Jesus in the Gospels and the work of the Holy Spirit in the subsequent New Testament writings. Pray for God to send the Holy Spirit to you that you might understand the great redemption that Christ has accomplished for all who believe. And I would admonish you to believe all that Christ has done, repent of your sin and follow after Christ in obedience to all that is commanded.

May God bless you with the eternal hope of redemption in Christ Jesus the Lord.