There're many who think that all Jesus came to do was to save us from sin; but that's just one side of the story. Yes, He saved us from our sins, but He did that for a purpose: so He could make us sons of God. His ultimate aim was to give us a new life, the God-life! It wasn't just to save us from our sins. Saving us from our sins was a means to an end.
Understand this: When He hung on the cross, and was crucified, you were in Him, because He did it for all men; He was made sin for us; He took our place. That's the legality of redemption. Even though you hadn't been born at the time He died, you were in Him. The same goes for all those who were born before He came—He was the representative of all men. When He died and was buried, in the mind of God, we all died and were buried in Him. And that was the end of sin. Our sin was buried with Him.
However, that wasn't the end of His substitutionary work. On the third day, God raised Him from the dead. And when He raised Jesus from the dead, we were also raised together with Him into a newness of life.
Remember, our sins were buried with Him. Our past with all the failures, weaknesses, and defeat were buried with Him. Now, you have a new life in Christ Jesus; not a continuation of your old life. You're a new creation now, superior to the devil, the world, and its systems.