John 17:20-23 - Jesus prayed that we would all be one so that the world would believe Jesus was sent by God. The idea is that we would love God so much that we will love each other better.
Do people see Jesus Christ in you? Do you love people where they are? Or do people see division amongst you (the people of God)?
(v 21) Jesus prayed to the Father that we will be one as He and the Father are one. Together, God can use us to do amazing things for His Kingdom. We will not be divided.
(v 22) Jesus says that He gave us the glory that the Father gave Him. 1 John 4:4 says "greater is He who is in me than He who is in the world." The greater one is inside of you! He prays that we be one as Jesus is one with the Father.
(v 23) Our purpose of oneness is so that the world can see and know that God loves us.