To say this is to misunderstand Lewis' understanding of how unfallen races and lands behave. The only reason we humans need a formalized religion, with services and sacraments and such, is that we've fallen from grace. Our lives are mostly lived for ourselves, so we need to set aside space and time to focus on our Creator and Redeemer. As Lewis expresses by analogy in Mere Christianity, we're foreign agents living in enemy-occupied territory, and worship services are like us assembling at a wireless to receive our instructions.Tash, I believe, is actually a demon, but there's nothing in Narnia to tell us where demons come from or even what they ARE. He is also the only god in Narnia to get a formal religion. I find it interesting that Lewis wrote a series with Christian overtones in which the only creature that is actually worshiped is an evil god. Not even Aslan and the Emperor are actually worshipped -- they merely recieve allegiance from the Narnians as higher royalty.
A land or race that had not fallen into sin would not need such mechanisms, because their entire lives would be worship. Everything they did or said would be an act of worship to God. For example, the races of Malacandra in Out of the Silent Planet have no religious observance, but they are in constant obedience to Oyarsa, the tutelary spirit put in authority over their planet. In Perelandra, the Green Lady need not practice any religion because she walks constantly in the presence of Maleldil (Christ).
The Christian Church teaches that there will come a day when sacraments are no longer needed, because mankind will dwell in God's presence an behold Him directly. Lewis' worlds are simply expressions of that reality in fiction.