Many people who are Christians will say of themselves they are sinners. I dispute that. If you're a sinner, you're an enemy of God. Romans 5:10 "We were God's enemies. . ." If you're saved, can you still be an enemy of God?
Jesus himself says in John 5:24, "Most assuredly, I say to you, he who hears My word and believes in Him who sent Me has everlasting life, and shall not come into judgment, but has passed from death to life."
What is the essence of Christianity if it isn't acknowledging your sinful nature and repenting of your sins, and in so doing, dying to the Law and being reborn in the Spirit? Being reborn in the Spirit, you are no longer a child of corruption, of this world. You are a child of God, the off-spring of your union with Jesus Christ. He remade you anew.
If you have been baptized in your heart with the blood of Jesus, you passed from death to life. You cannot be a sinner because Jesus washed away your sins and sinful nature. To call yourself a sinner after you have been reborn is to revert to being a subject of Satan, the Prince of this World. Satan is the enemy of God and he's happy to receive you back. He's happy you traded salvation for a lie.
What of our failings when we have moved from death to life? Aren't they sins? No, they're failings. If you were to take Jesus at his word, he is come back as your teacher. (1 John 2: 27 ) When you fail does your teacher condemn you? No, your teacher helps you to recognize your failing and correct it. You will delight in Jesus teaching you and correcting you.
So, if you've been baptized in your heart with the blood of Jesus Christ, give up the stumbling block, trade a lie for the truth of Jesus Christ: you've passed from death to life. Rejoice and Praise your Teacher!