Romans 16:17-18 I urge you, brothers, to watch out for those who cause divisions and put obstacles in your way that are contrary to the teaching you have learned. Keep away from them. For such people are not serving our Lord Christ, but their own appetites. By smooth talk and flattery they deceive the minds of naive people.
But whether it is older or newer understandings of sin we resist, and however preachers, teachers, and politicians may assist us in the resistance movement, each of us possesses one last defense against the knowledge of sin – a defense so strong, supple, mysterious and private that even veteran sinners cannot track its ways.
Self-deception is a shadowy phenomenon by which we pull the wool over some part of our own psyche. We put a move on ourselves. We deny, suppress, or minimize what we know to be true. We assert, adorn, and elevate what we know to be false. We prettify ugly realities and sell ourselves the prettified versions. Thus a liar might transform “I tell a lot of lies to shore up my pride” to “Occasionally, I finesse the truth in order to spare other people’s feelings.” We become our own dupes, playing the role of both perpetrator and victim. We know the truth – and yet we do not know it, because we persuade ourselves of its opposite. We actually forget that certain things are wrong and that we have done them. To the extent that we are self-deceived, we occupy a twilight zone in which we make up reality as we go along, a twilight zone in which the shortest distance between two points is a labyrinth.
Not the Way It’s Supposed to Be: A Breviary of Sin. Cornelius Plantinga, pg. 105