It is the belief that when God created us in the beginning, He made us perfect. He made us complete in all things. We didn't have any imperfections then. Our frame was perfectly good such that God look at everything which He has made and He said that they were good. We had no limitations then.
Limitations arose when the evil one came in and misled man to disobey the commandments of God. That singular act of disobedience drained out everything that is good from us and left us with all that is bad. Now man is full of several limitations. There are several things which we are unable to do or achieve.
The Lord Jesus Christ came to restore all that was lost. He came to put us back in our position of honour and dignity. The resurrection of Jesus Christ from the death brought back the lost glory of man. This is why are preaching the gospel. We preach the gospel to call men out of their positions of frustrations and failures into glory and honor.