v1-2: Paul's greeting; this is a personal letter, and 2 Timothy more so. He described Timothy as "my true son in the faith", see Phil 2.20. They shared the same desires and commitment to Christ.
v3-4: Paul had sent Timothy to Ephesus to sort out a range of problems. The section (to v11) brings an overview, and the rest of the letter deals with the various issues.
Timothy had apostolic authority, to lead and to teach.
There was error being taught, although not necessarily from 'the pulpit'. Timothy therefore had to teach the truth, and insist that others both obey and teach the same truth. False teaching promotes disputes; there was the problem of "myths and endless genealogies". In contrast, truth with faith brings godly edification.
The genealogies of the Bible are different, for they lead to, and end with, the Lord Jesus Christ. There seems to have been the influence of 'Judaizers', who based their teachings on the O.T. law, rather than on the grace to be found in Jesus Christ. Paul mentions the law, perhaps responding to those who had misused it.
v5: The necessity of a changed life, which is the evidence of true teaching; this is the goal of all who teach the word. This changed life is a thorough thing; emotional (love from a pure heart), moral (a good conscience), and doctrinal and practical (sincere faith). It is not the evidence of ritual or external rules.
v6-7: False teaching had already brought confusion; the false teachers were ignorant of the truth, and of the things they were saying. Personal experience, and a life of obeying the word, enables us to teach faithfully. In contrast to the false teachers, Paul had experienced the power of "the glorious gospel of the blessed God." He was therefore qualified to proclaim the gospel (Acts 9.15-16).
v8-11: For the age of grace, the law is part of the gospel. It is essential in that it exposes sins, but it cannot be the whole gospel. In Rom 7.10-13, we see that the law exposes sin and condemns it. The guilty sinner can therefore repent of his sins.
Here, sin is linked with false doctrine; anything that is contrary to sound doctrine is sin. The professing Christian who clings to his sins 'needs' false doctrine to justify his position.
Included in the list here is 'enslavers,' or slave traders. This became the key text for William Wilberforce's campaign against slavery in the nineteenth century.
v12: Paul was thankful to God; He had saved Paul, and called him to serve Him, and made him His servant. He had been counted faithful, not because of his past, but through His grace.
v13: Paul recognised that he had been a lawbreaker, a rebel, ungodly, and sinful (see v9). He had lived in unbelief, although, at the time, he had been convinced of his personal righteousness. He was a blasphemer (Acts 9.5). All such sins were now forgiven.
v14: The grace of our Lord; by which we are saved; we do not contribute any works of righteousness, for we have none. The Lord's grace was poured out abundantly. This is striking, since Paul was "a blasphemer and a persecutor and a violent man." Grace always comes to those who do not deserve it, for grace is, by its nature, undeserved. Paul is clear that he contributed nothing, but had received abundantly from Christ.
v15-16: Paul described himself as the chief of sinners, but he had been saved by the mercy and grace of God. The glorious truth is therefore that any may be saved. Christ's longsuffering was displayed in Paul, and can be displayed in any others also. Paul did not simply bemoan his sinfulness, but rejoiced in Christ's power to save and deliver.
Paul was bold enough to speak of himself as an example. He is the pattern for Timothy and for those in Ephesus, and for us also. There must therefore be a similarity of doctrine and practice.
v17: No wonder Paul responded in praise to Jesus Christ; superlatives and absolutes; words worthy of God alone.
Jonathan Edwards comments; 'as I read the words, there came into my soul a sense of glory of the divine Being; a new sense, quite different from anything I ever experienced before.'
He is eternal and immortal, beyond the power of death, unable to perish or die. Jesus Christ, the eternal King; He shares the eternal nature of God, Jehovah, see Rev 1.8, "who is, and who was, and who is to come."
He is invisible, beyond natural human perception.
He alone is wise, all-knowing, always right and true.
To Him be honour and glory for ever.
v18: Paul gave Timothy an instruction, a charge, a military command. Something given by the greater to the lesser. Timothy was subject to Paul, and doubtless recognised his spiritual authority, being full of God's grace. The commands were through a prophetic word, not from Paul's natural planning. Through obedience to these words, Timothy would fight a good warfare; this reflects the seriousness of his calling.
v19: Timothy had to hold on to faith and a good conscience, as in v5. Some had rejected these, with their false teachings. The human conscience is an important thing, and must be carefully guarded; Acts 24.16. It is potentially delicate, it is intuitive rather than rational, and it needs to be taught the way of Christ.
v20: To prove his point, Paul mentioned two, who were evidently known to Timothy, whom he had already delivered to Satan (1 Cor 5.5). The reason was false doctrine, from which they would not repent, rather than serious sin, although we understand that false doctrine promotes ungodly living.