Hi David, Faith is salvation, without faith one does not know Jesus.
But this faith or belief is in who Jesus is and what He has done. It is demonstrated in the life of the believer and how they interact.
This is Johns argument. Jesus and His presence in the heart of an individual will be demonstrated over time unmistakably.
Going on what Jesus said, every word will be looked at, every testimony, every action, to see what the testimony truly is.
Paul desired to take every thought captive, quite an aspiration.
Sometimes we think a hour long service once a week dedicated to Jesus is just too much.
But in reality if Christ is in our heart, everything we do needs to be guided, supported and dedicated to Jesus in prayer.
It is hard to think of something that will be ignored or left out.