Summary: 1) Religious Pride (Galatians 6:12a), by 2) Cowardice (Galatians 6:12b), and 3) Hypocrisy (Galatians 6:13).
This month, heavily armed assailants again attacked an Ebola treatment centre in the heart of eastern Congo’s deadly outbreak. Some community members wary of outsiders after years of deadly rebel attacks have shown hostility to health workers in a region that is facing its first Ebola outbreak. Distrust of the Ebola treatment has come from rumors that the centre is actually spreading the disease. The recent burning down of the treatment centre by locals was an effort in their minds to stop the spread of the virus. The most dangerous answer to a problem is the one that takes you away from the true solution.
The Judaizers that Paul has been dealing with as throughout the book of Galatians have sought to personally benefit themselves while giving the Galatians an artificial righteousness. Their glorifying in the flesh corrupts the true Gospel. Paul takes these closing verses of Galatians 6:11-13 to show the impact on the gospel summarizing his argument through the book. But he first deals with his own malady.
Paul explains in Galatians 6:11 “See with what large letters I am writing to you with my own hand”, that the autographed portion of the letter would include Gal. 6:11–18 and not the entire epistle (George, Timothy: Galatians. electronic ed. Nashville : Broadman & Holman Publishers, 2001, c1994 (Logos Library System; The New American Commentary 30), S. 431). In Koine (common) Greek quotation marks were not used. So emphasis was conveyed by enlarging the letters of the words written. Paul now personally picks up the pen and writes with large letters to emphasize his concluding words and to validate that the letter was genuine. Recall that the authority/authorship of Paul was challenged (Gal 1 & 2) (Anders, Max: Galatians-Colossians. Nashville, TN : Broadman & Holman Publishers, 1999 (Holman New Testament Commentary; Holman Reference 8), S. 80) The word for “letters” (grammasin) is plural and refers to the characters of the alphabet. Paul’s handwriting was large. (Beeke, J. R., Barrett, M. P. V., & Bilkes, G. M. (Eds.). (2014). The Reformation Heritage KJV Study Bible (p. 1698). Grand Rapids, MI: Reformation Heritage Books.)
Paul’s writing with … large letters may have been due poor eyesight, an affliction suggested in this letter. Shortly after speaking of having come to Galatia with “a bodily illness” (Gal. 4:13), the apostle expresses his gratitude to believers there for their willingness to “have plucked out [their] eyes and given them to [him]” (Gal. 15). If Paul’s “thorn in the flesh” (2 Cor. 12:7) did involve an eye disease, he understandably wrote in large letters in order to see what he was writing. Paul may have used the somewhat unsightly lettering as a statement, saying, in effect, “Because of my poor eyesight, you know how hard it is for me to write by my own hand, but what I have to say is so important and urgent that I want you to have this letter in your hands as soon as possible, with as bold lettering as possible. Unlike the Judaizers, Paul did not try to impress with scholarship, personal skills, or superficial formalities. This epistle is not written attractively, either, but I hope you will receive its message with the same urgency with which it is sent.”. Given the tone of the letter, the apostle sought in this way to give a final emphatic thrust to his message (Walvoord, John F. ; Zuck, Roy B. ; Dallas Theological Seminary: The Bible Knowledge Commentary : An Exposition of the Scriptures. Wheaton, IL : Victor Books, 1983-c1985, S. 2:610-611).
• Beware of appeals that emphasize presentation over content. Some of the shallowest, or misleading presentations are often the most glamoursly packaged. It can often be an intentional effort to bypass the mind to reach the emotions. When your actions are primarily based on transient feelings, they are often the most dangerous. They often fail to consider context, godly directives, and implications.
That Paul indicated that he is now writing: “with my own hand”, he is indicated that he normally dictated his letters to a scribe, or amanuensis, who did the actual writing. The epistle to the Romans identifies himself as Tertius (Rom. 16:22), a man about whom we otherwise know nothing ( Barnes, P. (2006). A Study Commentary on Galatians (p. 304). Darlington, England; Webster, New York: Evangelical Press.)
It was Paul’s custom, however, to write a short salutation in his own handwriting (see 1 Cor. 16:21; Col. 4:18; 2 Thess. 3:17) in order to prove the genuineness of the letter. During the time of the early church, many forged documents were circulated in the name of the apostles in order to gain credibility (Pseudopagraphia). Paul referred to that practice of deception when he cautioned the Thessalonian believers:
2 Thessalonians 2:2  not to be quickly shaken in mind or alarmed, either by a spirit or a spoken word, or a letter seeming to be from us, to the effect that the day of the Lord has come. (ESV)