2 Peter 1:5-9
And for this very reason, indeed, giving all diligence, add to your faith, courage; and to courage, knowledge;
2 Peter 2:20
Now, if, having fled away from the pollutions of the world, through the knowledge of the Lord and Saviour Jesus Christ, and being again entangled, they are overcome by them; their last condition is worse than the first.
1 John 2:3-4
And by this, we know that we have known him, if we keep his commandments.
1 John 2:19
They went away from us, but they were not of us. For, if they had been of us, they would have abode with us; but they went away, that they might be made manifest that they were not of us.