Albert Barnes Commentary Acts 5:39

"but if it is of God, ye will not be able to overthrow them; lest haply ye be found even to be fighting against God." — Acts 5:39 (ASV)

But if it be of God. If God is the Author of this religion. From this it seems that Gamaliel supposed that it was at least possible that this religion was Divine. He showed a far more candid mind than did the rest of the Jews; but still it does not appear that he was entirely convinced. The arguments which could not but stagger the Jewish Sanhedrin were those drawn from the resurrection of Jesus, the miracle on the day of Pentecost, the healing of the lame man in the temple, and the release of the apostles from the prison.

You cannot overthrow it. Because

1. God has almighty power and can execute his purposes;
2. Because he is unchanging and will not be diverted from his plans (Job 23:13–14).

The plan which God forms must be accomplished. All the devices of man are feebleness when opposed to him, and he can dash them in pieces in an instant. The prediction of Gamaliel has been fulfilled.

Men have opposed Christianity in every way, but in vain. They have reviled it; have persecuted it; have resorted to argument and to ridicule, to fire, and stake, and sword; they have called in the aid of science; but all has been in vain. The more it has been crushed, the more it has risen, and still exists with as much life and power as ever.

The preservation of this religion amid so much and so varied opposition proves that it is of God. No severer trial can await it than it has already experienced; and as it has survived so many storms and trials, we have every evidence that, according to the predictions, it is destined to live and to fill the world. (See Barnes' note on Matthew 16:18; Isaiah 54:17; Isaiah 55:11; Daniel 4:35).

Lest. That is, if you continue to oppose it, you may be found to have been opposing God.

Haply. Perhaps. In the Greek this is lest at any time; that is, at some future time, when too late to retract your doings, etc.

You be found. It will appear that you have been opposing God.

Even to fight against God. Greek, yeomacoi. This word occurs nowhere else in the New Testament. To fight against God is to oppose him, or to maintain an attitude of hostility against him.

It is an attitude that is most fearful in its character and will most certainly be attended with an overthrow. No condition can be more awful than such an opposition to the Almighty; no overthrow more terrible than that which must follow such opposition. (Acts 23:9).

Opposition to the gospel, in the Scriptures, is uniformly regarded as opposition to God (Matthew 12:30; Luke 11:23). Men may be said to fight against God in the following ways, or on the following subjects:

1. When they oppose his gospel, its preaching, its plans, its influence among men; when they endeavor to prevent its spread, or to withdraw their families and friends from its influence.
2. When they oppose the doctrines of the Bible. When they become angry that the real truths of religion are preached, and suffer themselves to be irritated and excited by an unwillingness that those doctrines should be true and should be presented to men. Yet this is no uncommon thing. Men by nature do not love those doctrines, and they are often indignant that they are preached. Some of the most angry feelings which men ever have arise from this source; and man can never find peace until he is willing that God's truth should exert its influence on his own soul, and rejoice that it is believed and loved by others.
3. Men oppose the law of God. It seems to them too stern and harsh. It condemns them; and they are unwilling that it should be applied to them. There is nothing which a sinner likes less than he does the pure and holy law of God.
4. Sinners fight against the providence of God. When he afflicts them, they rebel. When he takes away their health, or property, or friends, they murmur. They esteem him harsh and cruel; and, instead of finding peace by submission, they greatly aggravate their sufferings, and infuse a mixture of wormwood and gall into the cup, by murmuring and repining. There is no peace in affliction but in the feeling that God is right. And until this belief is cherished, the wicked will be like the troubled sea, which cannot rest, whose waters cast up mire and dirt (Isaiah 57:20). Such opposition to God is as wicked as it is foolish. The Lord gave, and has a right to remove our comforts; and we should be still, and know that he is God.
5. Sinners fight against God when they resist the influences of his Spirit; when they oppose serious thoughts; when they seek evil or frivolous companions and pleasures rather than submit to God; and when they resist all the entreaties of their friends to become Christians. All these may be the appeals which God is making to men to be prepared to meet him. And yet it is common for sinners thus to stifle conviction, and refuse even to think of their eternal welfare. Nothing can be an act of more direct and deliberate wickedness and folly than this. Without the aid of the Holy Spirit none can be saved; and to resist his influences is to put away the only prospect of eternal life. To do it is to do it over the grave; not knowing that another hour or day may be granted; and not knowing that, if life is prolonged, the Spirit will ever strive again with the heart.

In view of this verse we may remark:

1. That the path of wisdom is to submit at once to all the requirements of God. Without this, we must expect conflicts with him, and perils and ruin. No man can be opposed to God without endangering himself every minute.
2. Submission to God should be entire. It should extend to every doctrine and demand; every law, and every act of the Almighty. In all his requirements, and in all afflictions, we should submit to him, and thus only shall we find peace.
3. Infidels and scoffers will gain nothing by opposing God. They have thus far been thwarted and unsuccessful; and they will be still. None of their plans have succeeded; and the hope of destroying the Christian religion, after the efforts of almost two thousand years, must be vain, and will recoil with tremendous vengeance on those who make them.