God Himself is a mystery, and Christ is the mystery of this mystery. Surely we cannot fathom such a mystery simply by reading the letter of the Scriptures. Since Christ dwells in our spirit, we need to exercise our spirit in order to know Him as the mystery of God. Never regard Christ as a mere object to be known in an outward way. As the crucified and resurrected One, He is living both on the throne in the heavens and in our spirit as well. Hence, it is of utmost importance that we exercise our spirit to contact Him. This means that we must open up from the depths of our being and call on Him. Our spirit is our deepest part, deeper than the heart and all the parts of the soul. Therefore, to exercise our spirit is to open the deepest part of our being to call on the name of the Lord Jesus and to contact Him as the living One within us. To know Him, we must not only exercise our spirit, but also have our heart comforted. This means that our heart must be cherished, warmed. Moreover, our mind must be sober, our emotion must be regulated, and our will must be subdued. Every part of our inner being must be proper and function in a normal way. This is the reason Paul speaks of the hearts being comforted in relation to having the full knowledge of Christ as the mystery of God.