All of us has a tendency to minimize our own sin and maximize the sins of others against us. We tend to view the things we have done against God as the "small things" (we told a little white lie, or had a youthful moment of indiscretion). We view the things other people have done as the "big things."
The issue is that we try to be the ones who decide which sins are worse. Unfortunately, though, we don't get to be the judge of that.
Ultimately, I think in God's economy some of the "small" sins in our eyes might just be some of the "big" sins in his eyes. He separated all of humanity from Him for eating a piece of fruit, for goodness' sake. Certainly we would put "fruit eating" at the "small" end of the spectrum, right? But the deal is, it wasn't really about the fruit. It was about idolatry - believing they could be like God.
Idolatry is what sin boils down to. We believe someone else has a better plan than God, so we move forward serving that god. When we tell a little white lie, we are believing that something (or someone) is worth serving over and above the God of truth. When we fail to keep our word, we make a statement that something (or someone) is more important than God's command to be people whose "yes" means "yes" and "no" means "no." The small things are idolatrous every bit as much as if we were to switch religions altogether.
In that way, I think some of our smaller sins may just be the most offensive to God. The fact that we would abandon God as God or worship something other than God for something trivial like a little white lie or a moment of indiscretion has to be more offensive to God than if we had gone into sin whole hog.
When we minimize our own sin as something trivial, that might just make it more offensive.