Colossians 1:24

Who now rejoice in my sufferings for you - For you as a part of the Gentile world. It was not for the Colossians alone, but he regarded himself as suffering on account of his labors in preaching to the pagan at large. His trials at Rome had come upon him because he had maintained that the wall of partition between Jews and Gentiles was broken down, and that the gospel was to be preached indiscriminately to all mankind; see this illustrated in the introduction, Section 5.

And fill up that which is behind of the afflictions of Christ - That which I lack of coming up to the sufferings which Christ endured in the cause of the church. The apostle seems to mean:

(1)That be suffered in the same cause as that for which Christ suffered;

(2)That he endured the same kind of sufferings, to some extent, in reproaches, persecutions, and opposition from the world;

(3)That he had not yet suffered as much as Christ did in this cause, and, though be had suffered greatly, yet there was much that was lacking to make him equal in this respect to the Saviour; and,

(4)That he felt that it was an object to be earnestly desired to be made in all respects just like Christ, and that in his present circumstances he was fast filling up that which was lacking, so that he would have a more complete resemblance to him.

What he says here is based on the leading desire of his soul - the great principle of his life - to be just like Christ; alike in moral character, in suffering, and in destiny; see the notes at Philippians 3:10. Having this strong wish, he had been led to pursue a course of life which conducted him through trials strongly resembling those which Christ himself endured; and, as fast as possible, he was filling up that in which he now fell short. He does not mean that there was anything lacking or deficient in the sufferings which Christ endured in making an atonement which was to be supplied by his followers, so that their merits might be added to his in order to secure the salvation of men, as the Romanists seem to suppose; but that there was still much lacking on his part before he should be entirely conformed to the Saviour in his sufferings, and that his present condition was such as rapidly to fill that up. This seems to me to be the fair meaning of this expressions though not the one commonly given. The usual interpretation is, “that which remains to me of affliction to be endured in the cause of Christ.” But this seems to me to be cold and tame, and not to suit the genius of Paul.

In my flesh - In bodily sufferings.

For his body’s sake, which is the church - See the notes at Ephesians 1:23.