Jamieson, Fausset and Brown on Romans 1:5

5. By whom--as the ordained channel.

we have received grace--the whole "grace that bringeth salvation" (Tit 2:11).

and apostleship--for the publication of that "grace," and the organization of as many as receive it into churches of visible discipleship. (We prefer thus taking them as two distinct things, and not, with some good interpreters, as one--"the grace of apostleship").

for obedience to the faith--rather, "for the obedience of faith"--that is, in order to men's yielding themselves to the belief of God's saving message, which is the highest of all obedience.

for his name--that He might be glorified.