By the word of truth - That is, by making known the truths of the gospel. It was his object to make known the simple truth. He did not corrupt it by false mixtures of philosophy and human wisdom, but communicated it as it had been revealed to him. The object of the appointment of the Christian ministry is to make known the truth, and when that is done it cannot but be that they will commend their office and work to the favorable regards of people.
By the power of God - By the divine power which attended the preaching of the gospel. Most of the ancient commentators explain this of the power of working miracles - Bloomfield. But it probably includes all the displays of divine power which attended the propagation of the gospel, whether in the working of miracles, or in the conversion of people. If it be asked how Paul used this power so as to give no offence in the work of the ministry, it may be replied, that the miraculous endowments bestowed upon the apostles, the power of speaking foreign languages, etc., seem to have been bestowed upon them to be employed in the same way as were their natural faculties; see the notes on 1 Corinthians 14:32. The idea here is, that they used the great powers entrusted to them by God, not as impostors would have done, for the purposes of gain and ambition, or for vain display, but solely for the furtherance of the true religion, and the salvation of people. They thus showed that they were sent from God, as well by the nature of the powers with which they were entrusted, as by the manner in which they used them.
By the armor of righteousness on the right hand and on the left - Interpreters bare varied much in the exposition of this passage; and many have run into utter wildness. Grotius says, that it refers to the manner in which the ancient soldiers were armed. They bore a spear in their right hand, and a shield in the left. With the former they attacked their foes, with the later they made defense. Some have supposed that it refers to the fact that they were taught to use the sword with the left hand as well as with the right. The simple idea is, that they were completely armed. To be armed on the right hand and on the left is to be well armed, or entirely equipped. They went forth to conflict. They met persecution, opposition, and slander. As the soldier went well armed to battle, so did they. But the armor with which they met their foes, and which constituted their entire panoply, was a holy life. With that they met all the assaults of their enemies; with that all slander and persecution. That was their defense, and by that they hoped and expected to achieve their conquests. They had no swords, and spears, and helmets, and shields; no carnal weapons of offence and defense; but they expected to meet all their assaults, and to gain all their victories, by an upright and holy life.