Near the end of his life, Paul writes to encourage a young minister of the Gospel. Based on his exhortations, it seems that Timothy may be prone to fear, to being hesitant in proclaiming the Gospel when that proclamation leads to the stigma of imprisonment, as it did for Paul.
Paul reminds him not only of the wonderful message of the Gospel, that by grace we are delivered from sin and death to life and immortality, but also that having been entrusted with this message, Timothy is responsible to keep this trust and pass it on faithfully.
In this passage, Paul describes vividly our dreadful state prior to salvation and our glorious position in Christ. He also makes it plain that we are not saved by good works, but we are saved to do good works.
In the Mosaic law, the priesthood was restricted to a small number of Israelites. Only males of the tribe of Levi and the family of Aaron were priests, and even they could be disqualified by physical deformities or, temporarily, by ritual uncleanness. In contrast, under the new covenant established by Christ, all believers are called priests.