What does 2 Timothy 2:4 mean?

Paul continues his word picture of a soldier who shares in suffering for Christ from the last verse. Paul points out that soldiers don't concern themselves with non-military matters: they have a job to do. Nor do they worry about issues unrelated to their specific mission. In other words, a Roman soldier would not be distracted by "civilian" concerns: entertainment, politics, or weather, for example. Instead, his focus was entirely on fulfilling the orders of his commander. In this word picture, Christ is the one who has enlisted Timothy. His goal was not the trivial issues of life, but the mission for which God had called him.

Paul elsewhere used the concept of a soldier in relation to the discipline required in the Christian life (Phil 2:25). Believers who serve together are considered "fellow soldiers," a phrase Paul used as a positive reference to those who worked with him (Philippians 2:25; Philemon 1:2). In modern terms, this is like saying Christians are to be well trained and disciplined, like an experienced Marine who is prepared for any battle.