Hint: Don’t be either.
To call someone a “cretin” is to insult him as a person who is stupid, obtuse, or mentally defective. Even the world’s most famous composer was insulted by his employer with the epithet. Wolfgang Amadeus Mozart wrote to his father in May 1781 about a conversation he had where the Archbishop of Salzburg. During a heated
exchange while in Vienna, the Archbishop had called him a “cretin” because Mozart had not made plans to return to Salzburg as ordered and was unable to deliver a package in Salzburg for the Archbishop. This insult likely derived from the medical condition called cretinism. This medical condition is a congenital disease due to absence or deficiency of normal thyroid secretion, characterized by physical deformity, dwarfism, and mental retardation. Most etymologists believe the word cretin is a derivative of the Swiss-French Alpine dialect word créstin, which comes from the Latin word christianus or christianum. The use of “Christian” to describe people with such physical deformity or mental disability was probably as a reminder that those suffering from the unfortunate medical condition were still human creatures, created in the image of God, deserving respect. The term has become a pejorative now, that has been far removed from its original usage.
Some people mix up calling someone a “cretin” with calling him a “Cretan.” A Cretan is simply someone from Crete. However, in antiquity to be identified as a Cretan was to be linked with the moral decadence the ancient world associated with the people of Crete. Cicero wrote “[T]he rules of life are so contradictory that the Cretans…regard robbery as honorable.” Ancient Greek historian Polybius had a more biting estimation of the virtues of Cretans. “Now it would be impossible to find except in some rare instances personal conduct more treacherous or a public policy more unjust than in Crete.”
The Apostle Paul gets in the game of insulting Cretans when he wrote to Titus whom he established as the bishop on Crete to oversee several newly planted churches there. Paul counseled Titus against false teachers that were infiltrating the churches on Crete. “They must be silenced, since they are upsetting whole families by teaching for shameful gain what they ought not to teach.” (Titus 1:11). Paul then likely referred to Epimenides when he continued “One of the Cretans, a prophet of their own, said ‘Cretans are always liars, evil beasts, lazy gluttons’.” (Titus 1:12). Paul then affirms this accusation “This testimony is true. Therefore rebuke them sharply, that they may be sound in the faith….” (Titus 1:13). Paul, of course, meant this as a generalization and not that all Cretans cannot speak the truth, ever. These particular Cretans were leading the people of the Church astray. They claimed to know God but their behavior demonstrated their claims were a lie. “They profess to know God, but they deny him by their works. They are detestable, disobedient, unfit for any good work.” (Titus 1:16).
Paul called these false teachers liars and unbelievers because of their deeds and false teachings. He was not the least bit hesitant to make such a judgment. Defending the Church from such wolves evoked a strong response from Paul.
The Church is filled with both cretins and Cretans. There are those Christians who reject the intellectual side of Christianity for an emotional, if not lazy, faith that is easy. It takes no effort to feel. Feelings just happen to you. There is no work, no study, no diligence required. “God said it. I believe it. That settles it. I don’t need to know why what I believe is true. I just believe it. If I have the evidence, then I lack faith.” Such cretin Christians make the job of Cretan Christians easy because they lack the knowledge of the Word of God.
“Cretans” profess faith in God, but teach false doctrine and live lives that betray their profession. “Cretans” may be in leadership, or they may be merely laymen, but they teach a foreign gospel that makes light of sin, and shuns sound doctrine. They say things people want to hear. “Jesus is all about love, not judgment.” “He who is without sin cast the first stone means we are not to be judgmental.” “God wants us to be happy, so do good for yourselves.”
Faith is always linked to actions. Belief is always associated with behavior. A true confession of faith will ALWAYS be demonstrated by righteous living. Not that Christians never sin, but that the vector of their lives is always more holy, more righteous, more obedient. The process of sanctification is evident in a true Christian. We are known by our fruit. (Matthew 7:20).
Are we Cretans whose profession of faith is a lie? Are we cretins when it comes to sound doctrine because we have been following the teaching of “Cretans?” Perhaps our pews would be filled with fewer cretins when it comes to biblical orthodoxy if Christians would take a more manly approach to the teachings of Cretans, and expose them publicly like Paul did.
 Republic, Cicero 3.9.15. To be fair, Cicero was comparing several contradictory moral principles in the world at the time, and not just denigrating Cretans. The complete quote in its context reads “How many, such as the inhabitants of Taurica along the Euxine Sea—as the King of Egypt Busiris—as the Gauls and the Carthaginians—have thought it exceedingly pious and agreeable to the gods to sacrifice men. Besides these religious discrepancies, the rules of life are so contradictory that the Cretans and Ætolians regard robbery as honourable. And the Lacedæmonians say that their territory extends to all places which they can touch with a lance. The Athenians had a custom of swearing by a public proclamation, that all the lands which produced olives and corn were their own. The Gauls consider it a base employment to raise corn by agricultural labour, and go with arms in their hands, and mow down the harvests of neighbouring peoples. And our Romans, the most equitable of all nations, in order to raise the value of our vines and olives, do not permit the races beyond the Alps to cultivate either vineyards or oliveyards. In this respect, it is said, we act with prudence, but not with justice. You see then that wisdom and policy are not always the same as equity.”
 Histories, Polybius 6.47. “So just as when we observe the laws and customs of a p377 people to be good, we have no hesitation in pronouncing that the citizens and the state will consequently be good also, thus when we notice that men are covetous in their private lives and that their public actions are unjust, we are plainly justified in saying that their laws, their particular customs, and the state as a whole are bad. 5 Now it would be impossible to find except in some rare instances personal conduct more treacherous or a public policy more unjust than in Crete. 6 Holding then the Cretan constitution to be neither similar to that of Sparta nor in any way deserving of praise and imitation, I dismiss it from the comparison which I have proposed to make.”
 Some skeptics use this verse to discredit Paul, the New Testament, and the entirety of Christianity. Theirs is a rather silly argument, however. They say it is self-defeating to quote a Cretan (Epimenides) for the truthfulness that Cretans never tell the truth. The argument goes the Bible is supposed to be without error, but to have a Cretan say “Cretans are always liars” is logically impossible to defend. Yet, Paul says “This is a true testimony.” Therefore, the Bible is not inerrant, and the truth of the resurrection is now in doubt. See this lengthy, silly argument here http://www.jcnot4me.com/page37.html. It is amazing sometimes the lengths people will go to try to discredit Scripture. They blind themselves with vain, and silly objections to soothe their consciences from the guilt they feel for preferring their disobedience to surrendering to the sovereignty of Christ.