John Calvin's Commentary on the Bible

6 (1 Timothy 6:6)

Verse 6

6But godliness with sufficiency is great gain In an elegant manner, and with an ironical correction, he instantly throws back those very words in an opposite meaning, as if he had said — “They do wrong and wickedly, who make merchandise of the doctrine of Christ, as if ‘godliness were gain;’ though, undoubtedly, if we form a correct estimate of it, godliness is a great and abundant gain.” And he so calls it, because it brings to us full and perfect blessedness. Those men, therefore, are guilty of sacrilege, who, being bent on acquiring money, make godliness contribute to their gain. (119) But for our part, godliness is a very great gain to us, because, by means of it, we obtain the benefit, not only of being heirs of the world, but likewise of enjoying Christ and all his riches.

With sufficiency. (120) This may refer either to the disposition of the heart, or to the thing itself. If it be understood as referring to the heart, the meaning will be, that “godly persons, when they desire nothing, but are satisfied with their humble condition, have obtained very great gain.” If we understand it to be “sufficiency of wealth” (and, for my own part, I like this view quite as well as the other,) it will be a promise, like that in the book of Psalms,

“The lions wander about hungry and famished; but they that seek the Lord shall not be in want of any good thing.”
(
Psalms 34:10.)

The Lord is always present with his people, and, as far as is sufficient for their necessity, out of his fullness he bestows on each his portion. Thus true happiness consists in piety; and this sufficiency may be regarded as an increase of gain.

- John Calvin's Commentary on the Bible