For (eti gar). So most documents, but B reads ei ge which Westcott and Hort use in place of gar.
While we were yet weak (ontōn hēmōn asthenōn eti). Genitive absolute. The second eti (yet) here probably gave rise to the confusion of text over eti gar above.
In due season (kata kairon). Christ came into the world at the proper time, the fulness of the time (Gal 4:4; Eph 1:10; Tit 1:3).
I or the ungodly (huper asebōn). In behalf, instead of. See about huper on Gal 3:13 and also Rom 5:7 here.