Paul, an apostle of Christ Jesus by the command of God our Savior
Paul, in his self-description, emphasized his credentials (apostle) and authority (by the commandment of God). He did this both as a personal encouragement to Timothy and so the letter could be used as a letter of reference before any erring Ephesian Christians.
It seems that 1 Timothy was written by Paul to Timothy sometime after his release from Roman imprisonment as described at the end of Acts, and written from Macedonia (1 Timothy 1:3).
Apparently, after his release (hoped for in Philemon 1:22 and Philippians 1:25-26 and Philippians 2:24), Paul returned to the city of Ephesus. There he discovered that during his absence Ephesus had become a storm center of false teaching (a sad fulfillment of the prediction he had made to the Ephesian elders in Acts 20:29-30).
Paul probably dealt with the leaders of the heresy personally, but soon found it necessary to leave for Macedonia. He then left Timothy in charge of affairs at Ephesus, as his own personal representative. He knew that Timothy had a tough job to carry out, so he hoped that this letter would both equip and encourage him in the task.
–David Guzik (and following notes)
and of Christ Jesus our hope,
2 To Timothy my true son in the faith:
Paul could consider Timothy a true son in the faith because he probably led him and his mother to the Lord on Paul’s first missionary journey (Acts 14:8-20 and Acts 16:1).
Timothy was a resident of Lystra, a city in the province of Galatia (Acts 16:1-3). He was the son of a Greek father (Acts 16:2) and a Jewish mother named Eunice (2 Timothy 2:5). From his youth he was taught in the Scriptures by his mother and grandmother (2 Timothy 1:5; 2 Tim 3:15).
Grace, mercy and peace from God the Father and Christ Jesus our Lord.
Timothy Charged to Oppose False Teachers
3 As I urged you when I went into Macedonia, stay there in Ephesus so that you may command certain people not to teach false doctrines any longer 4 or to devote themselves to myths and endless genealogies. Such things promote controversial speculations rather than advancing God’s work—which is by faith.
Paul left the Ephesian Christians with a particular set of teachings (which he had received from Jesus and the Old Testament). He was concerned that Timothy did everything he could to make sure the Ephesians continue in that doctrine.
Paul did this because doctrine is vitally important to God. Today, what one believes — that is, their doctrine — is staggeringly unimportant to most people. This spirit of the modern age has also heavily influenced Christians. We live in a day where Pilate’s question What is truth? (John 18:38) is answered today, “Whatever it means to you.” But truth is important to God, and should be important to us. Remember that one of the pieces of the full armor of God is the belt of truth (Ephesians 6:14). Jesus said, “I am the way, the truth, and the life” (John 14:6). And we are told that “you will know the truth, and the truth will set you free” ((John 8:32).
5 The goal of this command is love, which comes from a pure heart and a good conscience and a sincere faith. 6 Some have departed from these and have turned to meaningless talk. 7 They want to be teachers of the law, but they do not know what they are talking about or what they so confidently affirm.
8 We know that the law is good if one uses it properly. 9 We also know that the law is made not for the righteous but for lawbreakers and rebels, the ungodly and sinful, the unholy and irreligious, for those who kill their fathers or mothers, for murderers, 10 for the sexually immoral, for those practicing homosexuality, for slave traders and liars and perjurers—and for whatever else is contrary to the sound doctrine 11 that conforms to the gospel concerning the glory of the blessed God, which he entrusted to me.
Paul tells Timothy that sound doctrine and right conduct are vitally connected.
The Lord’s Grace to Paul
12 I thank Christ Jesus our Lord, who has given me strength, that he considered me trustworthy, appointing me to his service. 13 Even though I was once a blasphemer and a persecutor and a violent man, I was shown mercy because I acted in ignorance and unbelief. 14 The grace of our Lord was poured out on me abundantly, along with the faith and love that are in Christ Jesus.
We often see our Christian service as a matter of volunteering. Yet as Christians, in regard to Jesus and His church, we are not volunteers. We are slaves. We are duty bound servants of Jesus, and faithfulness is expected of such servants. You don’t have to be smart to be faithful; you don’t have to be talented or gifted. Faithfulness is something very down-to-earth, and every one of us can be faithful in the sphere God has given us.
15 Here is a trustworthy saying that deserves full acceptance: Christ Jesus came into the world to save sinners—of whom I am the worst. 16 But for that very reason I was shown mercy so that in me, the worst of sinners, Christ Jesus might display his immense patience as an example for those who would believe in him and receive eternal life. 17 Now to the King eternal, immortal, invisible, the only God, be honor and glory for ever and ever. Amen.
The Charge to Timothy Renewed
18 Timothy, my son, I am giving you this command in keeping with the prophecies once made about you, so that by recalling them you may fight the battle well, 19 holding on to faith and a good conscience, which some have rejected and so have suffered shipwreck with regard to the faith. 20 Among them are Hymenaeus and Alexander, whom I have handed over to Satan to be taught not to blaspheme.
From verse 17: Now to the King eternal, immortal, invisible, the only God, be honor and glory for ever and ever. Amen.
HERE is a hymn (one of my favorite hymns!) based on this verse.