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

that they may all be one; even as you, Father, are in me, and I in you, that they also may be one in us; that the world may believe that you sent me.

Therefore, as for you, let that remain in you which you heard from the beginning. If that which you heard from the beginning remains in you, you also will remain in the Son, and in the Father.