You will also testify, because you have been with me from the beginning.
The Spirit will maintain Christ's cause against all opposition, testifying powerfully where we cannot. He is a distinct divine person, the Spirit of truth proceeding from the Father, sent to supply His bodily absence. Testimonies, the Spirit's principal witness and yours as apostles, are truth's proper support.
AI summary
Commenting on John 15:26-27
You will testify to the world that Jesus is the Messiah, and your testimony carries weight because you have been with Him from the beginning of His public ministry, witnessing His works and learning His doctrines for more than three years.
AI summary
ye also shall bear witness--rather, "are witnesses"; with reference indeed to their future witness-bearing, but putting the emphasis upon their present ample opportunities for acquiring their qualifications for that great office, inasmuch as they had been "with Him from the beginning." (See on Luk 1:2). Next: John Chapter 16