Now look at how Paul starts his letter. Paul wants to remind Timothy that it is by the authority of God that he is giving these final instructions. There is one path to take, one pattern for sound teaching and living, and it comes not from Paul's own authority, but straight from God. Grace, mercy and peace. That is what every Christian receives when we accept the gospel of Christ.
Grace is for the worthless.
It is God giving me what I don't deserve. Mercy is for the helpless. God not giving me what I do deserve, namely judgement. Peace is for the restless. The assurance that whatever happens to me will work out for God's glory.