Bible Verses About Union With Christ: Includes union with the Father

That they all may be one, as thou, Father, in me, and I in thee; that they also may be one in us: that the world may believe that thou hast sent me.

As for you, let that which you have heard from the beginning abide in you. If that abide in you, which you have heard from the beginning, you also shall abide in the Son and in the Father.