The meaning of the passage: “.. the Comforter, which is the Holy Ghost..”

“But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.” (St. John 14:26)

The passage in the Gospel of St. John 14:26, is a reference to the Revelation of Bahá’u’lláh, through Whose coming this prophecy was fulfilled. 
- Shoghi Effendi  (From a letter written on behalf of Shoghi Effendi to an individual believer, April 21, 1939; compilation: 'Lights of Guidance')

We are called upon to “follow” the “footsteps” of the disciples of Christ

It behoveth them not to rest for a moment, neither to seek repose. They must disperse themselves in every land, pass by every clime, and travel throughout all regions. Bestirred, without rest, and steadfast to the end, they must raise in every land the triumphal cry, Ya Baha'u'l-Abha! (O Thou the Glory of Glories).... The disciples of Christ forgot themselves and all earthly things, forsook all their cares and belongings, purged themselves of self and passion, and with absolute detachment scattered far and wide and engaged in calling the peoples of the world to the divine guidance; till at last they made the world another world, illumined the surface of the earth, and even to their last hour proved self-sacrificing in the pathway of that beloved one of God. Finally in various lands they suffered glorious martyrdom. Let them that are men of action follow in their footsteps! 
- ‘Abdu’l-Baha  (Quoted by Shoghi Effendi, The Unfolding Destiny of the British Baha'i Community)