Newton was the giant of the 18th Century although a great deal of his writing was done in the previous century. To go into his works would be too long and tedious. Hit the link to read more. The widely held religious principal of Deism, important to the USA, was largely based on Newton's science and uses that science to explain God, creation and the relationship of God, man and the physical earth. I suppose it would be safe to state that Deism was a product of Enlightenment thought but was greatly augmented by Newtonian science. Newton's influence cannot be overstated.

without his work in the feilds of physics would it even be studied today?

The laws of physics are a fascinating read even if you are a math dunce like me. . .it is hard to underrate or undervalue the immense contributions of Newton- a giant of science by any stretch of the imagination. . .

Isaac Netwon is one of the top physicists of all time. While not exactly how things work in all situations, Newtonian mechanics are dead on in the non-relativistic, macroscopic limit. You can derive the dynamics of almost any classical (meaning non-relativistic, non-quantum) system from Newton's Laws. Newton did his work over three hundred years ago, and the vast majority of his physics (I'm not going to get into his later philosophical writings, that's a trickier matter.) is completely valid in the right limits, which happens to include most of what we do on a daily basis. At this point I seriously wouldn't know how I could get by without knowing F=dp/dt (or F=ma with constant acceleration for those without calculus). 

EDIT: I forgot to add that he also came up with calculus at about the same time as Leibniz. They both claimed it, but either way an extremely influential discovery.

The greatest