The more you compare yourselves to others, the more you "see" that you are better, wiser, smarter, more holy than others, the bigger a jerk you will be. That's part of our sinful nature - we like comparing, we like elevating ourselves over others and ranking ourselves. And here is the danger - we think growth means that we *ought* to be able to see that growth in view of our neighbor (and his lack of growth).
I care nothing for comparing how well a Christian "performs". Growth in faith is not to be see by outside examination. Consider an analogy.
There are two athletes on your favorite sports team. One is a "star" - has brilliant talent... but sloughs off. He knows he's good -- and compared to many he is good. But he doesn't struggle and strive as much, doesn't practice hard - he knows how good he is. After all, he did _____ last season. The other athlete is also a star - an excellent player. But he realizes that while he may be a fine player, he's a little weak on _________, so he practices and practices, and strives to improve.
If you compare your actions with those around you, you will become morally lazy and spoiled. You will be like the overpaid "Star" athlete. You can always compare yourself to someone else who is lousy to feel good about yourself -- or even compare yourself to what you were a while ago.
On the other hand, if your focus is upon your own lack, your own need to improve, you will remain humble. It doesn't matter how much "better" you are now -- as you have grown, so have your standards. You see the areas in which you have to improve - and you work on those. Allen Iverson was willing to blow of practice - Michael Jordan spent hours upon hours improving things (he couldn't hit a jump shot to save his life when he first got in the NBA).
But there is another danger - you don't even have to compare yourselves to others to become a jerk. You can simply compare yourself to who you used to be, and be content with that. What do I mean? Well, let me tell you about my golf game.
When I started on the High School golf team my freshman year I would have thought shooting 50 for 9 holes was great (54 was more likely). By the time I was a senior, I wanted to be below 45. Was there improvement - sure. But, if I had said, "Ah, see, I have grown" -- what would happen? There would be no more improvement. Instead, as I improved I became more critical of my game. A shot that I would have been quite happy with as a freshman was by my senior year a horrible shot and unacceptable.
In fact, even now, when I only golf a couple of times a year, I'm still picky. On Friday I golfed for the second time this year -- the group in front of me was slow, so I played best ball with myself - hit each shot twice and took the best one. I shot par... which, viewed from the perspective of not golfing much isn't bad. But that's a rank amateur and indifferent view... if I were serious about golf, I'd be horrified at how many poor shots I hit.
The thing is - when we speak about living our lives as Christians... that's not a 2 or three times a summer thing if the weather is nice and not too windy -- that's every day. We aren't amateur Christians, or at least we aren't supposed to be.
So what does this mean? A Christian who grows in the faith learns to see his own sin more sharply, strives to do better. Yet at the same time, this clarity of vision and self-examination makes the love that Christ Jesus has for him all the more wonderful -- he understands just precisely how great Christ's love is, how much Christ actually did die for. He is freed from the self-justifying rat race and freed to simply strive after showing love to his neighbor and delighting in Christ's love.
Any focus on how much better you are than your neighbor, any smug satisfaction about how much wiser or better you are now than before destroys this. And that should be obvious -- those sorts of attitudes are all summed up under pride. Repent of pride, confess your sin, and receive Christ's forgiveness.