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That is a lot more helpful, seeing as though you were unclear about your original criteria.
Probably the single biggest difference is that scientists have defined what you need to build to be able to detect a gravity wave - the location of the device, the materials and setup required. We have one built now. Although it will take a long time to actually detect a wave (they have quite a long wavelength, so there is a low probability it will hit in the right manner) it has been built, and will be able to detect these waves.
No one religious, scientific, or otherwise, has tried to define what you need to detect the presence God, so that anyone that wishes to can construct this device, and go about "detecting" God. There are no blueprints, no plans, not even any ideas on how to do this, let alone attempt this.
I'd call that a pretty stark difference between gravity and God - one has a defined method of measuring it's presence that anyone can construct, the other does not.
Firstly, it is not me that wishes to detect God. I don't think God exists, so how can I define him, let alone attempt to detect him? If you want him to be detected by anyone, it is your job to come up with the equipment and materials required.
The evidence of gravity, or an effect that acts exactly as we understand gravity, are all around us. The way objects move when thrown, or when they are on the ground are all explained by gravity. That is hardly slim evidence.
Although I cannot explain how it comes about scientifically, (you raise a good point there) I do not pretend to, either. I can tell you many other things about gravity, though, such as how the gravity between two objects is modelled, the effects it has on other bodies, and how it affects many other things, such as, for example, creating surface tension on a liquid.
It more than adequately explains quite a lot of everyday phenomena.
As I have said, I know quite a lot about gravity, just not it's origin. I can explain how it affects a lot of real-world objects, for example, such as water, two different solids, and so forth.
I don't pretend to know how the universe was created, but I certainly do not pretend that I have an answer, called God, which really does not add to any explanation.
Changing the "the universe started on it's own, without direction" to "the universe started under the direction of God" does not explain anything. There is no answer to the mechanics used to start this process, for example. You certainly add the question of how God came about, why he done it, and so forth.