I think that to believers, Jesus is the projection of all the good things in their life. Their family and loved ones and all the things that they hold dear to their heart. This is why they defend and get so insulted when you question their faith in Jesus because it is so much a part of them that it is almost indistinguishable to them. They end up so that they cannot picture life without Jesus, so you hear things like "No faith in Jesus, you must hate yourself" or "Why don't atheists just kill themselves". They have their life so entwined with their faith in Jesus that life without Jesus just seems meaningless and devoid of morality or responsibilty. This leads to the "Without God, murder is ok" crowd who view atheism as this purely hedonistic lifestyle that is comparable with being criminally insane. (IMO, Atheism is not actually a lifestyle, for the record.)