There are two great temptations in the Christian life; and, in a certain sense, the better people are, the more susceptible they are to them. First, there is the temptation to try to earn God’s favour, and second, the temptation to use some little achievement to compare oneself with others to our advantage and their disadvantage. But the Christianity which has enough of self left in it to think that by its own efforts it can please God and that by its own achievements it can show itself superior to others is not true Christianity at all.

Barclay, William (2010-11-05). The Letters to the Galatians and Ephesians (New Daily Study Bible) (p. 26). Westminster John Knox Press. Kindle Edition.