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

that they may all be one; even as thou, Father, art in me, and I in thee, that they also may be in us: that the world may believe that thou didst send me.

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