This principle is usually mis-applied by atheists, to rule out the existence of God. So if they establish a natural causation they then believe that God is not necessary. Here is an example of such an argument;
" The bad weather was caused by low pressure, there is not a need for more causes, such as invisible pixies guiding the clouds into position. "
While this argument does have merit, as is obvious from the example, when you apply the argument to God, it is a mis-application. This is because, in this universe, there aren't always merely material or physical causes.
An example of this is motivational cause.
When somebody is murdered, there are physical causes, such as the means of weapon used, but there was also a motivation behind the killing. Perhaps the cause of the killing was revenge, or anger. This is not a physical cause, but a motivational cause, as someone was motivated to kill someone else by what they were feeling in their heart.
So now here is another example of Parsimony when it is incorrectly applied to God's existence;
" We don't need to understand why the person was murdered, we just have to establish who did it. "
As you can see, there is now a clear flaw in this reasoning because it is not necessarily unimportant as to whether there are OTHER causes.
So the atheist seems to assume that causes are mutually exclusive, or that there is only relevance to material causation, and there is an assumption that because natural processes don't require God, that He is then irrelevant or He is not needed. But as you can see, there may well be no universe at all, if God was not motivated to create it.
Even the weather can have a purpose, the rain brings water to give to the plants, etc....this might be God's motivational cause.
So for me, the atheist's use of Occam's razor, is usually a misunderstanding on their part.
So the principle of parsimony, while a useful axiom to rule out excessive entities and poor arguments, actually has nothing to do with God's existence, or his reasons and motivations. One scripture says; "My thoughts are higher than your thoughts, and my ways are higher than your ways". (paraphrase).