I John 1:1 “The elder unto the elect lady and her children, whom I love in the truth; and not I only, but also all they that have known the truth; 2 For the truth’s sake, which dwelleth in us, and shall be with us for ever.”
In this context, “the truth” is that Jesus Christ came to “save his people from their sins” (Matthew 1:21), “that he was buried, and that he rose again the third day according to the scriptures” (I Corinthians 15:4), that “he ascended up on high, he led captivity captive, and gave gifts unto men” (Ephesians 4:8), that “the promise that he hath promised us” is “eternal life” (I John 2:25), and that one Holy Day, “the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God” and raise all His Elect to Eternal life to be forever with him in our Heavenly Home (I Thessalonians 4:16-17). Furthermore, at the moment that the Holy Spirit gives us Spiritual Birth, we immediately know “the truth” Himself, Jesus Christ the Son of God (John 14:6); for, He plainly declared, “My sheep hear my voice, and I know them, and they follow me:” (John 10:27). John makes the point that, not only he, but “all they that have known the truth” “love” the “elect lady and her children” and that “love” is “in the truth”, not in any carnal attraction or motive! This pure “love in the truth” is a mighty force, given by God, that overcomes natural differences and binds the Children of God together. So mighty is this force, that the loving Children of God make the Church of Jesus Christ the focus and center of their lives, and often make great sacrifices just to be able to meet and worship with the blessed “elect lady and her children”.