2 John 1:4-6
It has given me great joy to find some of your children walking in the truth, just as the Father commanded us. And now, dear lady, I am not writing you a new command but one we have had from the beginning. I ask that we love one another. And this is love: that we walk in obedience to his commands. As you have heard from the beginning, his command is that you walk in love.
Ma. Lucia C. Natividad
Truth is to be understood in view of the apocalyptic and Wisdom tradition as the revelation of God’s mystery and His divine plan of salvation.
Truth in the Old Testament is descriptive of God. He is the truth for He keeps His promises as He did to his servant David: “Lord God you are God and your words are truth; you have made this generous promise to your servant” (2 Sam 7:28). “For the Lord’s word is true; all his works are trustworthy” (Ps 33:4). His ways are described as mercy and truth (Tob 3:2b). Israel, God’s people, is protected and redeemed through God’s kindness and truth: “Withhold not, O Lord, your compassion from me; may your kindness and your truth ever preserve me” (Ps 40:12b).
Those who trust in Him will gain the knowledge of God and of heavenly wisdom. “Those who trust in him shall understand truth” (Wisd 3:9). The truth of God demands that one loves the truth and observes it, and does what is right by the truth. In Tobit’s instructions to his son he said, “For if you are steadfast in your service, your good works will bring success, not only to you, but also to those who live uprightly” (Tob 4:6)….
The Son, sent from above, speaks only the truth which he heard from God (John 8:40) and what he has seen in the Father’s presence (John 8:38), for he is the only one who has seen the Father (John 1:18). He brought the truth from above, from the divine realm unattainable to man, down to earth, and reveals the truth in his very person, in his words and deeds and most fully on the cross. His words give expression to God’s truth: “For the One whom God has sent speaks the words of God” (John 3:34). He is the truth for he embodies the divine truth, and bears witness to the truth.
J.G. van der Watt
This brings us to an important point regarding the relation between aletheia (the truth) and agathos (the good). The frequency of the use of agathos is low in John’s Gospel (three times), while the frequency of aletheia and related words is high – it is a term John favours. Truth is indeed linked to all the important characters in the Gospel and is also a key concept in the letters of John. Although John knows the term agathos, he consciously prefers to express himself in terms of truth, but reminds us of the conceptual relation between the good and the truth. He indeed chooses not to use the well-known ancient moral term agathos, but prefers to express himself through the conceptual world covered by the concept of “truth”. “Doing the truth” in John 3:21 is directly linked to works done in God….
Good as concept is usually more related to the value aspect, while law is linked to the juridical aspect. The term truth semantically combines both areas, determining both what is “good” and what is “right”. It is right and it is good, because it is “truly divine”. The term truth covers a wider semantic range than either “the good” or “the law”. Truth is also personified in John – it is not abstractly defined or restricted to laws, but linked to Person(s). This gives the ethics of John a different character: it is relational ethics.
Catechism of the Catholic Church
The Old Testament attests that God is the source of all truth. His Word is truth. His Law is truth. His “faithfulness endures to all generations.” Since God is “true,” the members of his people are called to live in the truth….
To follow Jesus is to live in “the Spirit of truth,” whom the Father sends in his name and who leads “into all the truth.” …
Truth as uprightness in human action and speech is called truthfulness, sincerity, or candor. Truth or truthfulness is the virtue which consists in showing oneself true in deeds and truthful in words, and in guarding against duplicity, dissimulation, and hypocrisy….
The disciple of Christ consents to “live in the truth,” that is, in the simplicity of a life in conformity with the Lord’s example, abiding in his truth….