Union with Christ: Includes Union with the Father
Source: TTT
John 17:21
that all of them may be one, as You, Father, are in Me, and I am in You. May they also be in Us, so that the world may believe that You sent Me.
1 John 2:24
As for you, let what you have heard from the beginning remain in you. If it does, you will also remain in the Son and in the Father.