A believer should be able to live a life that reflects what he confesses. Living the Christian life is first about who we are before what we do. We are first called Christians because we are identified with Christ when we accepted him into our lives, then what we do comes second. The blood of Jesus can forgive our sins but it does not stop us from sinning.
It will still require our personal decision to either do what is right or what is wrong even after we have given our lives to Christ. Jesus did a permanent work for us by forgiving our sins with His blood. When Jesus died on the cross we died with Him, for those who accept Him in their lives. We have the experience of living above sin by recognizing that God has already dealt with sin in Christ.
One of the reasons why we struggle to live above sin and effectively with Christ is because we try to do it by our own strength. Here's what God's word tells us for those who try to achieve things by their own effort:
The word of God in the Bible made us know that by the arm of flesh no man shall prevail:
Zechariah 4:6
Then he answered and spake unto me, saying, This is the word of the LORD unto Zerubbabel, saying, Not by might, nor by power, but by my spirit, saith the LORD of hosts.
Whatever we are struggling with, be it sin or anything, our dependence should not be on ourselves but on God. The Christian life is a life of faith and not a life of struggle. God doesn't want us to struggle but to depend on Him.