Jesus said to his followers:

27 "Peace I leave with you. My peace I give to you; not as the world gives, give I to you. Don’t let your heart be troubled, neither let it be fearful. 28 You heard how I told you, ‘I go away, and I come to you.’ If you loved me, you would have rejoiced, because I said ‘I am going to my Father;’ for the Father is greater than I. 29 Now I have told you before it happens so that, when it happens, you may believe. 30 I will no more speak much with you, for the prince of the world comes, and he has nothing in me. 31 But that the world may know that I love the Father, and as the Father commanded me, even so I do."

John 14:27-31a - World English Bible

Jesus ended John 14 with a farewell. He gave them his peace ("Shalom" in Hebrew, the typical phrase for greeting and good-bye), for he was returning to his Father. In the greater scheme of things, the followers should rejoice, for his ascent home meant he realized his union with the Father and, implicitly, his followers would realize their union with God. Despite the activity of the Evil One (prince of this world), Jesus would reveal his love for the Father and his mission on behalf of the Father to the world, by dying on the cross.

When you look upon a crucifix, do you see Jesus fulfilling God's will? Do you see his unity with the Father?