Hashem is ONE, this is without a doubt the truth. Torah clearly emphasizes that a Jew must recognize the UNITY of Hashem in this world. But when a man looks at the world he doesn't see unity, he sees a lot of different forces which sometimes work together, but at other times these forces work against each other.
I believe that Hashem is the master of all the forces which we observe in the world. I believe that every thing which happens in the world, things we observe, are the direct result of Hashems providence. This ties in with the idea that the Torah often refers to G-d using two names, one is Elokim and the other YKVH (Hashem). When our experience with Hashem is a matter of nature we refer to him as Elokim, and when we are relating to his mercy we call him YKVH. This doesn't, Chas VaShalom, mean that there are two G-ds or even that sometimes Hashem is Mercy and sometimes he is Judgement/Nature. This is a incorrect understanding according to what I have learned.
Hashem has no limitations, he can act any way, but it will always be perceived by limited human beings as being either Hot or Cold, Good or Bad, Light or Dark, Mercy or Judgement.... We are limited, but Hashem is never limited. We refer to him based on our own subjective experiences.
This is how I understand the various eminations which are referred to in Kabbalah. They are not individual forces, they are names by which we relate to him, and our limited understanding allows us to have a better understanding that it is all coming from the ONE, the praised and beloved G-d of Abraham.
I don't want to get into a deep discussion of these topics because then it will require much more thought to write things which may be misinterpreted. Basically the concepts I discussed above explain my understanding of these ideas.