The Scofield Bible Commentary, by Cyrus Ingerson Scofield, [1917], at sacred-texts.com
fault
That is, sin.
(See Scofield) - (Rom 3:23).
communicate
Or, share with him. (Co1 9:7-15); (Ti1 5:18).
large
Greek, "with how large letters ... mine own hand." The apostle was, it appears from many considerations, afflicted with ophthalmia, a common disease in the East, to the point almost of total blindness, (for example), (Gal 4:13-15). Ordinarily, therefore, he dictated his letters. But now, having no amanuensis at hand, but urged by the spiritual danger of his dear Galatians, he writes, we cannot know with what pain and difficulty, with his own hand, in the "large letters" his darkened vision compelled him to use.
constrain you to be circumcised
"Circumcision" stands here for externality in religion -- form rather than spirit. (Col 2:16-23).
world
Greek, "kosmos", means "world-system". (Eph 2:2); (Joh 7:7).
(See Scofield) - (Rev 13:8).