Peace … love … faith … grace: These qualities are mentioned at the start of the letter (1:2, 15). Peace, love, faith, and grace are what Paul most desired for believers.
to the brothers: Paul uses this term to refer to all members of the same family, both male and female.
to all who love our Lord Jesus Christ with an undying love: Another way of translating this is "be eternally upon all who love our Lord Jesus Christ."