Our conversation was not about being sinless. You added that so you could beat it to death. We were conversing about keeping His commandments.
As a child of God, you should be encouraging others to keep them and obey God. Instead, you speak words of doubt and weakness.
Zacharias did not doubt God. Perhaps you should read it more carefully. He did not believe the words of an angel. I'm sure if an angel appeared before you and told you if you wanted you enter life, keep His commandments, you would doubt and not believe what he said, even though he stood in the presence of God.