“Therefore, my beloved brethren, be ye stedfast, unmoveable, always abounding in the work of the Lord, forasmuch as ye know that your labour is not in vain in the Lord” (I Cor. 15:58).
As we labor for the Lord, it is such an encouragement to know that, no matter what, our labor is not in vain in the Lord.
But if that be so, why did Paul tell the Galatians,
“Ye observe days, and months, and times, and years. I am afraid of you, lest I have bestowed upon you labour in vain” (Gal. 4:10,11).
And what about what the apostle told the Philippians:
“Do all things without murmurings and disputings…that I may rejoice in the day of Christ, that I have not run in vain, neither laboured in vain” (Phil. 2:14-16).
And don’t we find the same thought in I Thessalonians 3:5?
“…I sent to know your faith, lest by some means the tempter have tempted you, and our labour be in vain.”
If it was possible that Paul’s labor for the Lord might have been in vain, how could he tell the Corinthians that their labor could not be? How could the labor of a godly apostle be in vain, but not the labor of the carnal Corinthians?
We believe the answer is found in the context of the verse, where right before telling the Corinthians that their labor was not in vain, Paul spoke to them about the Rapture (I Cor. 15:51-57). In that day, when we stand before the Lord at the Judgment Seat of Christ, no believer’s labor will be in vain, for all of our labor for Him will be richly rewarded.
And so it is that, if the Galatians persisted in their legalism, if the Philippians continued to do things with murmurings and disputings, if the Thessalonians abandoned the faith, Paul’s labor among them would have been in vain in this life, but not in the next life! And if you are feeling discouraged about your labor for the Lord because people whom you have led to Him have departed from the faith, or believers to whom you’ve introduced the grace message have turned their back on that blessed truth, you too can rejoice that your labor is not in vain in the Lord! source