Unto me, who am less than the least of all saints - This is one of the class of expressions unique to Paul. The ordinary terms of language do not express the idea which he wishes to convey, and a word is therefore coined to convey an idea more emphatically; compare the notes at 2 Corinthians 4:17. The word used here - ἐλαχιστότερος elachistoteros - does not occur elsewhere in the New Testament. It is a comparative made from the superlative. Similar expressions are found, however, in later Greek writers; see Bloomfield and Rosenmuller for examples. The word means here, “who am incomparably the least of all the saints; or who am not worthy to be reckoned among the saints.” It is expressive of the deep sense which he had of the sinfulness of his past life; of his guilt in persecuting the church and the Saviour; and perhaps of his sense of his low attainments in piety; see the notes at 1 Corinthians 15:9. Paul never could forget the guilt of his former life; never forget the time when he was engaged in persecuting the church of God.
The unsearchable riches of Christ - On the word “riches,” as used by Paul, see the notes at Ephesians 1:7. The word rendered “unsearchable,” ἀνεξιχνίαστον anexichniaston, occurs but once elsewhere in the New Testament Romans 11:33, where it is rendered “past finding out;” see the notes at that verse. It means that which cannot be “traced out,” or explored; which is inscrutable, or incomprehensible. The meaning here is, that there was a “sufficiency” in Christ which could not be traced out or explored. It was wholly incomprehensible. The fullness of the riches in him could not be appreciated. There is no more emphatic expression in the New Testament than this. It shows that the heart of the apostle was full of admiration of the sufficiency and glory that was in the Saviour; that he wanted words to express it; and that he considered it the highest honor to be permitted to tell the world that there were such riches in the Redeemer.