John Calvin Commentary Acts 16:5

"So the churches were strengthened in the faith, and increased in number daily." — Acts 16:5 (ASV)

The churches were confirmed. From this we gather that what Luke sets down, or rather touched upon concerning the decrees of the apostles, was, so to speak, inserted incidentally, not being very relevant to the matter. For he commends a far different fruit of Paul’s doctrine when he says that the churches were confirmed in the faith.

Therefore, Paul so ordered external things that he was principally careful for the kingdom of God, which consists in the doctrine of the gospel and far surpasses and surmounts external order. Therefore, those decrees were mentioned insofar as they were helpful for maintaining concord, so that we might know that the holy man cared about it.

But religion and godliness have the primary place, their sole foundation being faith, which in turn rests upon the pure Word of God and does not depend on human laws.

Now, by this example, Luke urges us forward to proceed continually, lest, at the beginning, sloth or neglect of making progress come upon us. Also, the way to increase faith is expressed, namely, when the Lord stirs us up by the diligent work of His servants, as at that time He used the labor and diligence of Paul and his companions.

When he immediately adds that they were also increased in number, he commends another fruit of preaching; and yet he thereby also signifies to us that the more those who are first called grow in faith, the more they bring others to Christ, as if faith spreads to others through its branches.