Who is claiming to be without sin?
John is writing about individual sin. We as Christians have to confess our sins to Christ. Not once saved always saved. You can see my original post.
We are not Robots. It is relationship with God. Two way street. Not everything is done and we walk in between the raindrops.
When we walk past the Pearly Gates of Heaven and we know for sure that we are at least 5 feet past then we are truly saved. Then we never will be tempted again by the enemy. But in the mean time we are still on earth. The enemy will still tempt us.