“But in this matter it is specially to be noted that the doctrine of Christ is to be faithfully proclaimed not only in the public gatherings of the church, but also in the home and to each one individually, following the example of Paul in the third and fifth texts. Thus in the third text [Acts 20:18-21] he states: I have proclaimed the doctrine of Christ to you and taught you in the general and public assembly, δημοσίᾳ– and also privately from house to house, κατ’ οἴκους. And afterwards: For three years I never stopped warning each of you day and night. And in the fifth text [1 Thess. 2:5-12]: Like a father his children I have warned each one of you &c. The doctrine of the holy gospel is the doctrine of eternal salvation, and on account of our corrupt nature there is nothing more difficult and troublesome for us to learn; that is why this doctrine requires the most faithful, earnest and persistent teaching, instruction and admonition that anyone could ever employ.”
Martin Bucer, Concerning The True Care Of Souls: p 181.