Not the outward form of godliness, but its inward substance with contentment is great gain--gain not of a worldly, but of a spiritual nature.

Supreme regard to God, grateful obedience to his commands, cheerful submission to his dealings, and contentment with the allotments of his providence, will, through grace, gain all needed good in life, in death, and for ever.

A man possessed of true godliness is a gaining, thriving, man: such as are godly, or truly gracious, they are come into good and happy circumstances, and are possessor of the true,solid, satisfying, durable, and unsearchable riches of grace; all their debts are paid, they are richly clothed, and deliciously fed, and are in a good
family, even the household of God, who before were in debt, arrayed in
rags, were in a starving condition, and strangers and foreigners; yea, they
are heirs of God, joint heirs with Christ, and have both a right and a
meetness for the heavenly inheritance; they are now made kings and priests
to God, and, in the present state of things, have God to be their portion,
and exceeding great reward; they have an interest in Christ, and in all
spiritual blessings in him, and have the Spirit as the earnest of their future
inheritance; they are rich in faith, and in good works; their souls, which
were lost, are gained, and shall be saved with an everlasting salvation; and
ere long they will be possessed of all the riches of glory, signified by a
house not made with hands, a city which has foundations, whose builder
and maker is God, an incorruptible inheritance, and a kingdom and glory:
how great is the gain of godliness!

and such a man is content with what he has, and thankful for it, submits quietly to the will of God, and patiently bears every adverse providence: and this is now the fruit and effect of godliness, or true grace, and is a considerable part of that gain which godliness brings with it; and such a man is a happy man indeed, let his circumstances be what they will.

godly persons, when they desire nothing, but are satisfied with
their humble condition, have obtained very great gain.

if a man have but a little in this world, yet, if he have but enough to carry him through it, he needs desire no more, his godliness with that will be his great gain.

A Christian's gain is great: it is not like the little gain of worldlings,
who are so fond of a little worldly advantage.

Death is called an unclothing; it unclothes the body, disrobing it of all its gaudy and glorious attire: yea, it unclothes the bones; our flesh wears off quickly in the grave. We proverbially say of a rich man, he has left a vast estate, left it behind him, carrying neither a foot of land, nor a farthing of money with him; therefore doth St. Paul add, it is certain we can carry nothing out.

Contentment is a sedate and quiet temper of mind about outward things

That godliness is the sincere practice of the Christian religion, so called, because it directeth and prescribeth to us the true and only way of worshipping and serving God.

If there be true religion, united with its proper accompaniment, peace of mind, it is to be regarded as the true riches. The object of the apostle seems to be, to rebuke those who supposed that property constituted everything that was worth living for. He tells them, therefore, that the true gain, the real riches which we ought to seek, is religion, with a contented mind. This does more to promote happiness than wealth can ever do, and this is what should be regarded as the great object of life.

The meaning is, that real religion should be regarded as the greatest and most valuable acquisition.