I thought it is
Breath
I am the posterchild for what the Buddhists believe yet they don't worship me
In Buddhism, breath remains perennial and can be seen as the "poster-child". In Maha Rahulovada Sutra,it is said that Buddha told his son, “This is the practice of mindfulness of breath, Rahula. This is how the sincere practice of mindfulness of breath is of great fruit, of great benefit. If mindfulness of breath is practiced continuously, then your last breath will be in knowing, not in unknowing.” Yet, at the same time, breath is not worshiped but practiced.
My cycle is eternal yet death follows me
The cycle of breath is eternal with each breath being a new one when you inhale in but dies as you inhale out
Some see me as a wish granter and my opposite slumbers beneath
As a breath renews,there is life. Once it stopped, one dies
If I cry for you, you will be relieved
As we breathe in, the air goes through our nose and the breath "cries" so that our breath gets warm and wet to prevent irritation of the cell when the air gets into our lungs.
Title: I am found everywhere and yet nowhere
Everyone you see you know they are breathing and you "find" them breathing but yet at the same time you cant see breath and wont think much of it