"1 Timothy is not simply a moralistic manual for church conduct. It is rather a call to Christ-centered, gospel-centered godliness for the sake of the church - and a lost world."

Hughes, R. Kent. "Introduction to 1 Timothy." Introduction. ESV Gospel Transformation Bible. Ed. Bryan Chapell. Wheaton: Crossway, 2013. 1629.

Why Paul wrote to Timothy?

Paul wrote 1 Timothy in order to advise his young coworker Timothy concerning issues that were arising at the church in Ephesus. When Paul left Timothy in Ephesus, he had specifically charged him to deal with some false teachers in the church (1:3). Since Paul was then separated from Timothy and the church, he wrote back to him with further instructions. He hoped to return for a visit but wrote in the meantime to address the way in which Christians should behave (3:14–15). Throughout the letter Paul grounds Christian behavior in the gospel.

The false teachers are the primary occasion for the letter. The letter as a whole is bracketed by discussion of the false teaching, and the positive instruction is crafted in direct contrast to the false teachers. The exact nature of the false teaching is unclear. It apparently involved speculation about the law (1:7–11) and asceticism (4:1–5). Paul’s real concern is with the results of the false teaching—for example, promoting speculations (1:4; 6:4), arrogance (6:4), and greed (6:5–10). Paul addresses the content of the false teaching only in passing but focuses on the fact that true Christianity is evidenced by lifestyles shaped by the gospel. Those whose lives are not shaped by the gospel show that they have turned away from the faith (1:6, 19–20; 4:1; 5:6, 8, 11–12, 15; 6:9–10).

First Timothy is a clear call for the church to live out in tangible ways the ethical implications of the gospel.

Van Neste, Ray. "Introduction of 1 Timothy." Introduction. The ESV Study Bible. Ed. Wayne Grudem. Wheaton, IL: Crossway, 2008. 2322. Print.