I. The purpose of Timothy's mission to the Thessalonians was to establish, to make them steadfast in the midst of persecution, to make them rooted and grounded in love, to make their very trials serve that all-important end, that they, as a church, might cast forth roots like Lebanon. The work of establishing them is, strictly speaking, God's work. But it is here none the less ascribed to Timothy, spoken of as his work, because he is a fellow-labourer with God.
II. The reason for the "steadfast endurance" is given in the words which follow: "For yourselves, know that we are appointed thereunto." This knowledge they had, both from apostolic teaching and their own personal experience, the knowledge that tribulation is the common lot of Christ's people. The world's scorn and enmity cannot fail to be excited by the Christian's character and conduct. Hence, holiness entails suffering as well as sin does, for sin will, in some way or other, persecute it.
III. In every case of resistance to the Tempter there is new accession of spiritual strength to the believer himself. In fighting the good fight of faith, in overcoming the Evil One, we gain new power. As the South Sea islanders imagine that the prowess and valour of the enemies they slay in battle pass over into themselves, so in truth is it with the soldiers of the Cross. The very force and strength of the temptations which he overthrows become his own. Therefore the exhortation of Ignatius, in his epistle to Polycarp, has a meaning for all time: "Stand firm as the anvil under its repeated blows; for a great combatant must not only be buffeted, but must also prevail."
J. Hutchison, Lectures on Thessalonians,p. 105.
References: 1 Thessalonians 3:2. Preacher's Monthly,vol. vi., p. 321. 1 Thessalonians 3:5. Clergyman's Magazine,vol. ii., p. 55. 1 Thessalonians 3:6. J. Irons, Thursday Penny Pulpit,vol. vi., p. 197.