Our holiness is our conformity and obedience to the will of God.
God rejects any attempt at holiness which is resolved only into the doctrines or precepts of men (Isa 29:13, 14). So for men to pretend to possess or exercise a holiness, from a principle within, without respect unto the commands of God without, as given in his word, is to make themselves their own god, and to despise obedience unto him who is over all, God blessed for ever.
Then are we the servants of God, then are we the disciples of Christ, when we do what is commanded us, and because it is commanded us in Holy Scripture.
Adapted from The Works of John Owen, 3:605.