Panentheism literally means "everything is in God".
It is a philosophical/theological concept that seems hard to define and has many variants. It is important to question whether or not it is true, that is biblical, however, it might be a case of splitting theological hairs. One has to ask what difference it actually makes.
Supportive of Panentheism
Opposed To Panentheism
All Is Not One: The Problem With Panentheism And The Material World - David W. Jones (Centre For faith And Culture)
What's Wrong With Panentheism? - Roger E. Olson (Patheos)
Process Theology: A Survey And An Appraisal - Norman L Geisler AND William D Watkins (Themelios). This article equates Process Theology and Panentheism