Does the following Christian philosophy make sense to most atheists?
I doubt it makes sense to any atheists, let alone most, because it just doesn’t make sense. I assume you are trying to set out a logical argument with premises and a conclusion .I recommend you read ‘Logic ‘ by Wilfred Hodges to help you understand how logic works. In essence you are making the mistake of confusing concept with existence – just because you can think of something doesn’t mean it exists, that’s one of the wonders of the human mind – we can make things up. God is just one of the many things humans have invented.
This is a modified form of the ontological proof o the existence of god. It does not work. Yes I nave a ‘concept’ of god just like I have a concept of Harry Potter. So Harry Potter must exist. The definition of god for an atheist is by definition that which does not exist. So in direct answer to your question – No Christian philosophy does not make any sense to me. Indeed it is just nonsense.