The trendy embrace the term 'spirituality' but shun its close cousin, ‘religion.’ I had a politically correct Jewish professor in my kitchen a while back whose husband had converted from Roman Catholicism to Judaism. I asked her why he had changed his religion. She objected to the term ‘religion,’ explaining that his change was a ‘spiritual’ one.
How typical. Being a good host, I didn't lay into her as I probably should have for her 'spiritual' good.
Etymologically, ‘religion’ suggests a binding, a God-man ligature, so to speak. But trendy New Age types don’t want to be bound by anything, or submit to anything. I suggest that this is part of the explanation of the favoring of the S word over the R word. Another part of the explanation is political. To those with a Leftward tilt, ‘religion’ reminds them of the Religious Right whose power strikes them as ominous while that of the Religious Left is no cause for concern.
A third part of the explanation may be that religion is closely allied with morality, while spirituality is often portrayed as beyond morality with its dualism of good and evil. One of the worst features of New Age types is their conceit that they are beyond duality when they are firmly enmired in it. Perhaps the truly enlightened are beyond moral dualism and can live free of moral injunctions. But what often happens in practice is that spiritual aspirants and gurus fall into ordinary immorality while pretending to have transcended it. One may recall the famous cases of Rajneesh and Chogyam Trungpa. According to one report, ". . . Trungpa slept with a different woman every night in order to transmit the teaching to them. L. intimated that it was really a hardship for Trungpa to do this, but it was his duty in order to spread the dharma."
With apologies to the shade of Jack Kerouac, you could say that that gives new meaning to 'dharma bum.'