There is almost a little four-point recipe for resisting heresy and false teaching, even in its mildest, early stages in this verse. First of all, ‘be rooted.
‘Rooted,’ that means daily Scripture reading. The tree puts down its roots. Built up no doubt refers to progressive sanctification, every day concerned about holiness. ‘And stablished in the faith, as ye have been taught.’ Remembering the things taught. ‘Oh no, I do not do that’, we say. ‘I sit in the pew, I enjoy the sermon, an hour afterwards it has gone from my mind. The next service I will enjoy another sermon and it will be gone from my mind. Years ago, we say I used to reflect, yes, I remember and I used to ask myself – what did I learn today? And I used to make some notes when things appealed to me, a great promise of God, a great doctrine. And it made these things stable in my mind. But I have long left off doing that.’ What a shame. You are ripe for an attack of the enemy of souls.