There is a duty incumbent on every man to instruct others, according to his ability and opportunity, in the knowledge of God; the law of which, being natural and eternal, is always obligatory on all sorts of persons. […] The highest degree in religion which men now aim at is but to attend to and learn by the public teaching of the ministry. And, alas, how few are there who do it conscientiously, to the glory of God and the spiritual benefit of their own souls! The whole business of teaching and learning the knowledge of God is generally turned into a formal spending, if not squander of so much time. But as for the teaching of others according to ability and opportunity, to endeavor for abilities, or to seek for opportunities of it, it is not only for the most part neglected, but despised. How few there are who take any care to instruct their own children and servants! But to carry this duty farther, according to opportunities of instructing others, is a thing that would be looked on almost as madness, in the days in which we live. We have far more that mutually teach one another sin, folly, yea, villainy of all sorts, than the knowledge of God and the duty we owe to him. This is… what God… has given up careless, unbelieving professors of the gospel to, in a way of vengeance (Covenant Theology: From Adam to Christ, 296).