Speak the things which are fitting for sound doctrine
What we say and do needs to match what we believe about the Bible:
If we believe that God is omniscient, then we will keep our thoughts pure, loving and right.
If we believe that God is holy, then we will strive to live holy lives and will confess sin and forsake it quickly.
If we believe that God can only do what is best, then we will trust Him completely.
If we believe that Jesus is the only one who can give salvation from sin, then we will pray only to Him and ask Him to help us not to sin.
Be diligent to present yourself approved to God
as a workman who does not need to be ashamed,
accurately handling the word of truth.
But avoid worldly and empty chatter,
for it will lead to further ungodliness,
and their talk will spread like gangrene.
2 Timothy 2:15-17a
Therefore, brethren, be all the more diligent
to make certain about His calling and choosing you;
for as long as you practice these things, you will never stumble;
2 Peter 2:10
Little children, let us not love with word or with tongue,
but in deed and truth.
We will know by this that we are of the truth,
and will assure our heart before Him in whatever our heart condemns us;
for God is greater than our heart and knows all things.
Beloved, if our heart does not condemn us, we have confidence before God;
and whatever we ask we receive from Him,
because we keep His commandments and do the things that are pleasing in His sight.
This is His commandment, that we believe in the name of His Son Jesus Christ,
and love one another, just as He commanded us.
The one who keeps His commandments abides in Him, and He in him.
We know by this that He abides in us, by the Spirit whom He has given us.
1 John 3:18-24