The letter of John is a letter written by an elder statesman in the Church, (probably the apostle John) encouraging his flock in the face of many difficulties to hold on to things of first importance. The things John teaches have become his habit and practice through long usage. They are habits and disciplines that are transformational if we can acquire them. They form a secret history with practical outworkings.
We live in an age of ‘fake news’ and image driven lifestyle communication, where Truth is a rare commodity. Jesus was so committed to truth that he said/implied that if we swore an oath instead of letting our yes be yes and our no be no it was from the evil one (father of lies) and indication that our words are not trustworthy.(matt 5:37)