There is nothing new under the sun. Though Solomon said this around 1000 B. C., it still rings true almost three thousand years later. Babies are born, grow old, and die, but as they do they pass along the same old rotten sinful nature to their children. Here, junior, a little present from dad.
Sin is a constant in the human race, and so certain patterns of behavior are predictable.
Granted, the trappings of sin change with the seasons, but the perverse essence of sin remains. No, we prefer acts of supererogation that are manifestly more hip . Real godliness is hard work, a fact that Scripture illustrates with a number of metaphors. With such a big job facing us it is no marvel we are tempted to fake it. So each pocket of Christians establishes their own extra-biblical criteria they use to identify godliness.