Stephen, your simplistic explanation of sin is in fact making things even more difficult and complicated for Christians and it illustrates how the western and modern mindset warps what sin has always been throughout the Scriptures, which was specifically a judicial matter and violation of a commandment. If you take a look at the Jewish view of sin (and Jesus did teach and preach in a Jewish environment since there were no “Christian Churches” when he was around), he spoke in the context of his people and their judicial understanding of sin.

Sin therefore, in the Jewish context, was not a state of being as you are implying by using the word “disease” but rather something on does, or an act. Jesus therefore did not come to heal a disease as you are suggesting, otherwise no Christians would ever commit sins. Rather Jesus brought a solution to deal with the consequences of sin, which makes the act ultimately irellevant. It is about God, not about what you do or do not do, thus dealing with the consequences is indirectly dealing with the act.

God therefore expects willing hearts to act accordingly out of love for God, not fearful hearts to do so.