Because Jesus was tempted, we know that being tempted is not a sin in itself. But Jesus said if you look at someone in lust, it is committing adultery, which is sin. Since both are in the mind and not an action, how do you distinguish between being tempted and lusting?
This is an excellent question. For many people, the idea between being tempted and actually lusting after something is difficult, if not impossible, to distinguish.
But the best way to identify and distinguish between temptation and lust is to use an example from our current world of personal computers. Imagine you�re surfing the Internet and looking at a webpage. The page itself looks pretty normal, but as you scroll down you discover a small photo of a woman in a bikini that catches your attention. The heading under the photo suggests that by clicking the image you will get to see more. At this point you are tempted. If you click away from the page or close the browser, it is nothing more than a temptation. But the moment you click on the image, the temptation has merged with your will, and you are now pursuing in the form of lust.
You see, temptation steps over the line and becomes sin when it is able to unite with my will. And whether that action includes the click of a mouse or some other kind of pursuit, it is at that point a sinful action. James refers to this as the point when �desire has conceived.� (James 1:15)