But without those components could the thing actually exist?
In the example of the universe - possibly. A universe empty of matter and energy could possibly exist.
God cannot be broken down, and the necessary entity cannot be broken down.
Jeremy beat me to it, but the paradoxical nature of the Trinity suggests that the Christian conventional view is that God can, and often is, broken down. You counter with the notion:
Without Ice, steam and water could H2O exist?
Notwithstanding the sophistry of things like other states of matter, the point is that water is broken down and some of it can be ice whilst some of it is steam and other bits are liquid. For a period, if you accept Christian dogma, part of 'god' was manifest on Earth as a physical human being ('The Son') - if that was the whole of God, was there no 'Holy Ghost' or 'Father' at that time, or can God be broken down?
Surely contingent things are part of the universe.
Maybe, maybe not. Contingency requires time, but time as we understand came into being with the universe, so the whole concept of the universe being contingent or otherwise may be nonsensical. Given how time appears to work, existence is a four-dimensional array, and whilst within the universe we can assess an idea of contingency as a description of the shape of the universe at a given point, the universe is the whole of space-time - time itself is one of those components of the universe, and therefore contingency of the universe itself is at best complicated, and at worst meaningless.
Since nothing is contingent on itself i.e. it is contingent on something else or exists necessarily then in order not to fall into absurdity you would have to propose a non contingent entity from which all contingent things arose
Again, no. I'm still awaiting any sort of rational explanation for why an infinite regress is problematic.
Again to avoid absurdity we must avoid circular contingency. Here you seem to be suggesting that there is a separate entity from which contingent things arise and I have no beef with that
To be clear, I don't see that an 'unmoved mover' is necessary, but given that you've posited one I'm highlighting possibilities that seem to call your assumptions into question.
O.