That believers ought to be simple, with prudence
In the Gospel according to Matthew: “Be prudent as serpents, and simple as doves.” And again: “You are the salt of the earth. But if the salt have lost his savour, in what shall it be salted? It is good for nothing, but to be cast out abroad, and to be trodden under foot of men.”
Source: The Treatises of Cyprian (New Advent)