God is not mocked. The design of this observation is to reply to the dishonest excuses which are frequently pleaded. One alleges that he has a family to support, and another asserts that he has no superfluity of wealth to spend in liberality or profusion. The consequence is, that, while such multitudes withhold their aid, the few persons who do their duty are generally unable to contribute the necessary support. These apologies Paul utterly rejects, for a reason which the world little considers, that this transaction is with God. The supply of a man's bodily wants is not the sole question, but involves the degree of our regard for Christ and his gospel. This passage contains evidence that the custom of treating faithful ministers with scorn did not originate in the present day; but their wicked taunts will not pass unpunished. For whatsoever a man soweth. Our liberality is restrained by the supposition, that whatever passes into the hands of another is lost to ourselves, and by the alarm we feel about our own prospects in life. Paul meets these views by a comparison drawn from seed-time, which, he tells us, is a fit representation of acts of beneficence. On this subject we had occasion to speak, in expounding the Second Epistle to the Corinthians, where the same metaphor was employed. Happy would it be for us, if this truth were deeply impressed upon our minds. How "very gladly" would we "spend and be spent" (2-Corinthians 12:15) for the good of our neighbours, encouraged by the hope of the coming harvest! No operation is more cheerfully performed by husbandmen than throwing the seed into the ground. They are enabled to wait with patience during nine months of the year, by the expectation of reaping a corruptible harvest, while our minds are not properly affected by the hope of a blessed immortality.

Be not deceived - That is, in regard to your character, and your hopes for eternity. This is a formula of introduction to some admonition that is especially weighty and important. It implies that there was danger that they would be deceived in reference to their character. The sources of the danger were the corruption of their own hearts, the difficulty of knowing their true character, the instructions of false teachers, etc.; see the note at 1-Corinthians 6:9.
God is not mocked - He cannot be imposed on, or mocked. He knows what our real character is, and he will judge us accordingly. The word rendered "mocked" (μυκτηρίζω muktērizō), means, properly, to turn up the nose in scorn; hence, to mock, or deride, or insult. The sense is, that God could not be imposed on, or could not be insulted with impunity, or successfully. To mock is, properly:
(1) To imitate, to mimic: to imitate in contempt or derision.
(2) to deride, to laugh at, to ridicule.
(3) to defeat, or to illude, or to disappoint.
(4) to fool, to tantalize - Webster.
Here it cannot mean to imitate, or to mimic, but it refers to the principles of the divine administration, and must mean that they could not be treated with contempt, or successfully evaded. They could not hope to illude or impose on God. His principles of government were settled, and they could not impose on him. To what the reference is here, is not perfectly plain. In the connection in which it stands, it seems to refer to the support of the ministers of the gospel; and Paul introduces the general principle, that as a man sows he will reap, to show them what will be the effect of a liberal and proper use of their property. If they made a proper use of it; if they employed it for benevolent purposes; if they appropriated what they should to the support of religion, they would reap accordingly. God could not be imposed on in regard to this. They could not make him think that they had true religion when they were sowing to the flesh, and when they were spending their money in purchasing pleasure, and in luxury and vanity.
No zeal, however ardent; no prayers, however fervent or long, no professions, however loud, would impose on God. And to make such prayers, and to manifest such zeal and such strong professions, while the heart was with the world, and they were spending their money for every thing else but religion, was mocking God. Alas, how much mockery of God like this still prevails! How much, when people seem disposed to make God believe that they are exceedingly zealous and devoted, while their heart is truly with the world! How many long prayers are offered; how much zeal is shown; how many warm professions are made, as if to make God and man believe that the heart was truly engaged in the cause of religion, while little or nothing is given in the cause of benevolence; while the ministers of religion are suffered to starve; and while the "loud professor" rolls in wealth, and is distinguished for luxury of living, for gaiety of apparel, for splendor of equipage, and for extravagance in parties of pleasure! Such professors attempt to mock God. They are really sowing to the flesh; and of the flesh they must reap corruption.
For whatsoever a man soweth - See the note at 2-Corinthians 9:6. This figure is taken from agriculture. A man who sows wheat, shall reap wheat; he who sows barley, shall reap barley; he who sows cockle, shall reap cockle. Every kind of grain will produce grain like itself. So it is in regard to our works. He who is liberal, shall be dealt with liberally; he who is righteous, shall be rewarded; he who is a sinner, shall reap according to his deeds.

Be not deceived - Neither deceive yourselves, nor permit yourselves to be deceived by others. He seems to refer to the Judaizing teachers.
God is not mocked - Ye cannot deceive him, and he will not permit you to mock him with pretended instead of real services.
Whatsoever a man soweth - Whatsoever kind of grain a man sows in his field, of that shall he reap; for no other species of grain can proceed from that which is sown. Darnel will not produce wheat, nor wheat, darnel.

(6) Be not deceived; God is not mocked: for whatsoever a man soweth, that shall he also reap.
(6) He commends liberality towards the poor, and first of all chides those who were not ashamed to pretend this and that, and all because they would not help their neighbours, as though they could deceive God. And afterward he compares alms to a spiritual sowing which will have a most plentiful harvest, so that it will be very profitable: and compares being a covetous miser to sowing carnally, from which nothing can be gathered but such things as fade away, and eventually perish.

Be not deceived,.... By false teachers, who, in order to engross all to themselves, dissuaded the Galatians from communicating to their honourable pastors, and faithful ministers of the word; or by themselves, who being of a tenacious and covetous disposition, devised various things to excuse them from performing this their duty to the preachers of the Gospel; as that they had families of their own to maintain, that their circumstances were such that they could give little or nothing this way, and the others, who were of better abilities in life, ought to bear this charge; and with such like things endeavoured to satisfy their consciences in the neglect of their duty: but this was all self-deception, for
God is not mocked; nor will he be; men may deceive themselves, and others, with such excuses and false appearances, yet they cannot deceive God, who knows their hearts as well as their worldly substance, and that the omission of their duty arises not from want of ability, but from a covetous temper; and who looks upon withholding from his ministers that which is due unto them as mocking of him, and which he will not suffer with impunity:
for whatsoever a man soweth, that shall he also reap; as to kind, quality, and quantity, generally speaking; if he sows wheat he reaps wheat, if he sows barley he reaps barley; no man can expect to reap another sort than what he sows; and if it is good seed he may hope for a good crop; and if he sows bountifully, he shall reap bountifully; but if he sows sparingly, he shall reap sparingly; and if he sows nothing, he can never reap anything. This is a proverbial expression, and may be applied to all actions, good and bad, and the reward and punishment of them, and particularly to acts of beneficence, and the enjoying of the fruits thereof; See Gill on 2-Corinthians 9:6.

God is not mocked--The Greek verb is, literally, to sneer with the nostrils drawn up in contempt. God does not suffer Himself to be imposed on by empty words: He will judge according to works, which are seeds sown for eternity of either joy or woe. Excuses for illiberality in God's cause (Galatians 6:6) seem valid before men, but are not so before God (Psalm 50:21).
soweth--especially of his resources (2-Corinthians 9:6).
that--Greek, "this"; this and nothing else.
reap--at the harvest, the end of the world (Matthew 13:39).

Be not deceived. Men often are. They do fancy that God may be mocked. The immutable law of the spiritual kingdom shows that he is not.
Whatsoever a man soweth, that shall he also reap. A law not only of the vegetable world, but of our bodies and spirits. Habit is only an illustration of this law. The delirium tremens on the one hand, and the purity of the aged saint on the other are due to the action of this law.
Soweth to his flesh. He who thus sows will reap a crop of fleshly lusts and ills. His carnal indulgence will end in moral ruin.
Soweth to the Spirit. He shall reap spiritually, and as a final harvest the spiritual life beyond, the life everlasting.
Let us not be weary in well doing. In sowing to the Spirit. Because, if we hold out faithful, and faint not, we are sure to reap in due season.
As we have therefore opportunity. Doing good is well doing, i. e., sowing to the Spirit. The Christian rule is to do good, but above all others to love, cherish and help the brethren.

God is not mocked - Although they attempt to mock him, who think to reap otherwise than they sow.