This is a popular law that most of us know, I don't think I need to stay long on this. A threshold is the bottom-most part of a doorway that one crosses to enter, you cannot enter a house without crossing the threshold. In the ancient time among the Semitic people the father is the family's priest and the altar of sacrifice is at the threshold. It is at the threshold that animals are sacrificed. When God called Moses to the mountain and told him the design of the temple, the altar of sacrifice was to be placed at the entrance of the temple.
You cannot enter the temple without passing the altar—here embodies a spiritual principle. The altar of the Old Testament represent the cross of the New Testament, it is located at the threshold (the entrance). To enter into any dimension of Christ you will find the cross at the threshold. If you want to move from one level of the dimension to another you will still find the cross at the threshold of the next dimension. The cross is at every threshold, the deeper the cross is worked into your life, the more depth you will have in Christ. Yes, to grow deep in Christ you must allow the cross work deep in you.
"that I may know Him and the power of His resurrection, and the fellowship of His sufferings, being conformed to His death" (Phil 3:10).
To attain the fullness of Christ you must experience the fullness of the cross. You must become completely conformed to his death. The more you are conform to his death, the more of his fullness you will have access to. So if you want to enjoy Christ, you must be ready to suffer the cross. The purpose of the cross is to kill the carnal man in you. Everything that is of the carnal man must die because you're entering into a completely new creation, and there is no place for the carnal man here. This new creation is too holy to harbor any piece of the carnal man.