With respect to the wicked, the Blessed Holy One indeed does change…

"I am G‑d, I do not change." (Malachi 3:6) The Tikunei Zohar 26 (70b) comments that with respect to the wicked, the Blessed Holy One indeed does change. He clothes Himself with numerous garments, concealments and husks, these being Chaos, Desolation and Darkness. (see Gen. 1:2) It is thus written, "I will hide My face from them". (Deut. 32:20) But toward those who depend on Him and His Divine Presence, He indeed does not change.

We therefore see that the Blessed Holy One conceals Himself with many covers and garments…

I heard from my master [the Baal Shem Tov] that when a person realizes that the Blessed One is hidden, this concealment actually ceases to exist. For then, "all the workers of iniquity crumble." (Psalms 92:10) Extraneous thoughts…are merely the garments and coverings in which the Blessed Holy One hides…

It is therefore written, "Hide, I will hide My face from them". (Deut. 31:18) This means that the Blessed Holy One will hide Himself in such a manner that they will not know that He is there…

I heard a similar thing from my master. It is written, "The enemy said: I will pursue, I will overtake…"(Exodus 15:9) [In the Hebrew,] the first five words in this verse begin with the letter alef. This indicates that G‑d, the Master (in Hebrew, "Aluf", related to the letter alef) of the universe, is even there [in the deeds of the enemy]…

If a person is aware of this important principle, he will realize that there can be no barrier separating him from his G‑d while he is praying and studying. Even though he may have many extraneous thoughts, they are merely the garments and coverings in which the Blessed Holy One hides. But when one knows that the Blessed Holy One is concealed there, then there is no concealment.

[Translation and commentary by Rabbi Aryeh Kaplan from Toldot Yaakov Yosef; from The Chasidic Masters/Moznaim Press]