Jn 17:21-23
Jesus showed that He was the only begotten Son of God. So Jesus and God are one. (Jn 10:30-33,38)
Jn 10:30 I and my Father are one. 31 Then the Jews took up stones again to stone him. 32 Jesus answered them, Many good works have I shewed you from my Father; for which of those works do ye stone me? 33 The Jews answered him, saying, For a good work we stone thee not; but for blasphemy; and because that thou, being a man, makest thyself God. 38 But if I do, though ye believe not me, believe the works: that ye may know, and believe, that the Father is in me, and I in him.
Jesus died on the cross to save us from our sins and make us children of God. (Jn 17:21-23)
Jn 17:21 That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me. 22 And the glory which thou gavest me I have given them; that they may be one, even as we are one: 23 I in them, and thou in me, that they may be made perfect in one; and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me.