Jesus considered it a sin. What is human nature to us, as we have a sinful nature, can be a sin to God. Now, what Jesus was saying too, is that NOBODY is sinless, it is impossible having been born with a sinful nature. It is the essence of the Law, just like John says if you hate your brother without cause, it is the same as murder to God, who is perfect. It is the essence. The Law shows us that we are sinners, it leads us to our Saviour, who paid the penalty of sin for all, which is death. By one man, Adam, sin came into the world and was passed down to all men, and by one man, born of the seed of a woman, conceived of the Holy Spirit, not a man, the sin debt was paid in full, all we have to do is believe in Him, that His death was sufficient, that God was as Isaiah says, 'satisfied', as in satisfied with the payment, it was enough to pay for all the sins of all the world, ever. The moment we trust in Christ, our sins are considered paid in full, we do not have to ever suffer for any sin we ever have, or will commit, (although their are consequences-pain, suffering in this world and loss of reward in the next), and we have Christ's righteousness imputed unto us, in place of our own.