This is the philosophy part. Also, Arizal does not agree with pantheism. To the Arial (and the Zohar), only Azilut is godliness, not the lower worlds. Also the Zimzum has nothing to do with pantheism. To use the issue of the Zimzum was a smoke screen made up by chasidim to try to show why the Gra put Chasidim (or rather "the disciples of the Magid from Metzritch") in cherem. but the Gra does not mention the zimum. Also it is not relevant. Hashem might have condensed his light or Himself and still everything might not be godliness; i.e. it could be he condensed his light or himself. Then he sent down his light into the empty space and made the lower worlds. That still does not mean that the lower world are Divine. It is simply irrelevant. And in fact, anyway it says in many places in the beginning of the Eitz Chayim that Hashem condensed Himself.
To sum this up simply the faith of the Torah is monotheism. This goes for the Rambam and Saadia Geon and the Arizal. The principle of creation something from nothing is the basis for Torah as the Rambam also holds. Something from nothing does not mean something from ain sof (infinity). So for chasidim to present pantheism as kabalah or as Judaism is not right.