The doctrine of sinless perfection teaches that over time a believer in Christ can develop a lifestyle that reaches a level of sinlessness.
Most believers in Jesus go through a period of progressive sanctification. Sanctification is the process of living a life that decreases in sin. In other words, it's the process of being more the kind of person that does the right thing in God's eyes and less like the kind of person we was before we decided to be a Christian. The Bible does teach that sanctification exists but that it is a process. Some move along faster than others but none arrive at the point to where there is no more sin left in their life. There is always room to improve our spiritual walk.
A believer in Jesus still sins although it should be less and less as time goes on. Temptations still come our way and sometimes we resist them and other times we don't even though we know that is wrong. It's the human part of us. Our faith in Christ should strengthen us far beyond where we were in life before becoming a Christian....there by the process of sanctification occurs...sinning less because we have greater strength to resist.
A sinless life does not occur until after death when the Christian goes to heaven. That is made possible because Jesus paid the price for our sins...all of them! He could do that because He Himself is the only sinless one who ever lived (Hebrews 4:15). Until that time occurs the sanctification process is progressive and remains progressive until death.
Sinless perfection is not possible and is a false doctrine.
The Old and New Testament backs up this position with verses such as:
Other articles of Interest include:
Israel My Glory a Ministry of the Friends of Israel Gospel Ministries, Inc. January/February 2014 pp.22-23 by Thomas C. Simcox.