A complaint that I often hear is that it is difficult to comprehend how Jews can be so unethical when it comes to money matters. It is particularly painful when the dishonest Jew in question is supposedly religious.
It's a horrible feeling to be cheated when the cheater seems to have no conscious when it comes to keeping his word or being honest. We shake our heads in disbelief and wonder how it is possible for another Jew to act in such a deplorable manner.
I have always felt that everything comes down to a lack of יראת שמים, fear of Heaven. If one truly fears G-d and understands that he is accountable for his actions, he would not dare harm another person in any way at all. This is the real test of one's level of religiosity. Does he have Yirat Shamayim or not?
The Talmud in Brachot 6b, speaks of the merits of the G-d fearing Jew. One who has fear of G-d will have his words heard by his peers. Rabbi Elazar said that the whole world was created for the G-d fearing Jew.
Maybe the Gemara is telling us that the world can only retain its sense of sanity and goodness without the G-d fearing. Without them, the world would be left with dishonest thieves.