Are you good enough?

I just started a new job a couple weeks ago and found a key in one of my drawers. I had assumed the key was to unlock the elevator. Well this morning I had the opportunity to give it a try, and it seems I am still not sure what the key is for. All this reminded me about something I had thought a while back.
Keys are made for specific locks. A key that is made for my car will not open your car door. (Well, my mom did have one time when a friend of hers had locked her keys in her car and my mom's key opened her door, but that was a miracle and doesn't count.)
The key you have may work well for your life, you might even feel happy and fulfilled. However, when you die you will come to a door whose lock your key will not open. What it comes down to is thinking you are good enough on your own to get into heaven is like taking your own house key and trying to use it on your neighbors door.