I like the question, if you'll pardon my saying so. Not enough people ask the basic questions and get tripped up by it, later on. Jesus is one part of the Holy Trinity, wholly God and man. -As God, he is incapable of sin because of his divinity. (In fact, no sin can abide in or with a Holy God.) His sinless nature made him the sin offering, begun in the Old Testament, for our sins. Just as the blood of unblemished sacrificial animals were once offered in the temple. That is where we get the Lord's Supper, where we remember His sacrifice for our sins. I hope that others can offer more, as I know that there are others that are far more knowledgeable than I. I just wanted to answer the question because it is a very good one.