Now you know what is restraining him, to the end that he may be revealed in his own season.
The word here is in the neuter gender, “What withholdeth.” In the following verse it is in the masculine gender, ὁ κατέχων ho katechōn - “he that letteth,” or withholdeth; and the reference would seem to be to some agency or state of things under the control of an individual, or of some civil power, that then operated as a restraint on the natural tendency of things. Of this, the apostle says, they had had full information; but we can only conjecture what it was. The restraining power of anything controlled by an individual, or of any government, or the restraining power of God, would meet all that the phrase implies. The most natural interpretation is that which refers it to civil power, meaning that there was something in the form of the existing administration which would prevent this development until that restraint should be removed. The supposition that there was even then a tendency to concentrate all ecclesiastical power at Rome, and that while the civil authority remained there it would not suffer ecclesiastical power to grow to the exorbitant height which it ultimately reached, will meet all that is implied in the language.