I do not believe piety requires the notion of a personified deity. There are those who sense the sacred all around them without such images. In fact, many of those who must declare themselves to be atheists in this culture, would be considered great mystics in a culture with a wider religious imagination.
Jürgen Habermas once gave an obituary to the philosopher, Richard Rorty which makes this point very clear, at least to me.
“One small autobiographical piece by Rorty bears the title ‘Wild Orchids and Trotsky.’ In it, Rorty describes how as a youth he ambled around the blooming hillside in north-west New Jersey, and breathed in the stunning odour of the orchids. Around the same time he discovered a fascinating book at the home of his leftist parents, defending Leon Trotsky against Stalin. This was the origin of the vision that the young Rorty took with him to college: philosophy is there to reconcile the celestial beauty of orchids with Trotsky’s dream of justice on earth. Nothing is sacred to Rorty the ironist. Asked at the end of his life about the ‘holy’, the strict atheist answered with words reminiscent of the young Hegel: ‘My sense of the holy is bound up with the hope that some day my remote descendants will live in a global civilization in which love is pretty much the only law.”
If anyone cannot hear the same music of the Sermon on the Mount, or Isaiah, the Bhagavad Gita, or Buddha’s Dhammapada playing behind the words of that charitable atheist, we might question whether they have ears to hear.