On Jesus' last night on earth, with His disciples, His final prayer lets them know that He has full authority over the people that God has sent Him to save. (John 17). He had already told them that the Holy Spirit would bring His truth.
How does this happen? St Paul tells the Colossians "We continually ask God to fill you with the knowledge of His will through all the wisdom and understanding that the Spirit gives, so that you may live a life worthy of the Lord and please Him in every way..." (Colossians 1:9b-10) So God fills us with wisdom and understanding through the Spirit; Jesus has made peace through His blood. In comparison, what can we do? Nothing--except to be open to what He does to us and through us.
St Paul takes this to a whole different level. He puts it this way:" ..He is the Head of the Body, the Church; He is the beginning and the firstborn from among the dead, so that in everything He might have the supremacy; For God was pleased to have all His fullness dwell in Him, and through Him to reconcile to Himself all things, whether things on earth or things in Heaven, by making peace through His blood shed on the cross." (Colossians 1:18-20)
He sees us as One Body, being presented to God by His Son, our Redeemer. He calls us to come together as one body in peace and worship Him. He also calls us to be parts of this body as individuals with spiritual gifts that the church and the world needs, and also in small groups who also have varied spiritual gifts and callings which complement each other, so that the whole is greater than the sum of the parts. And we are also called to teach and disciple others, both within the fellowship and outside. In our physical bodies, parts that don't get proper nutrition and use become toxic to the whole body. This applies to the church body as well. Parts that don't stay healthy and perform their design function will damage or even kill the body. We are all in this body together!