A simple general relativity theory for objects moving in gravitational fields is developed based on studying the behavior of an atom in a gravitational field and maintaining the principle of relativity. The theory complies with all the known effects of gravity such as the gravitational time dilation and faster light speeds higher in the gravitational field. The field equations are applied to calculate the satellite time dilation in any orbit, the light deflection by the sun, and the anomalous advance of Mercury?s perihelion. In all these calculations, the results matched observations with an error of less than 1%. The approach to the new theory introduced here is different from the geometric approach used by the general relativity theory. The theory is field based where the potential energy of a system of masses can be easily calculated and the force can be found as the gradient of the potential field in analogy to Newtonian mechanics. The resulting field equations become the traditional Newton?s equations when week gravitational effects are present. The special relativity theory of an object moving without experiencing gravitational fields can be derived directly from the gravitational field equations introduced here. The theory introduced here has several differences from the general relativity theory. For example, the event horizon of a black hole (where light cannot escape) has to be of zero radius, essentially meaning that light can escape any object unless the object has infinite density. Another primary consequence of this study is that the principle of equivalence of gravitational and inertial mass has limited validity and a new definition of gravitational mass is given here. Besides its extreme simplicity as compared to general relativity, the new theory removes all the known infinities and puzzles that can result from the general relativity theory and Newtonian mechanics. In addition, the new theory is in full compliance with quantum mechanical concepts and it is shown that the very essence of quantum mechanics is gravitational in nature and that electrons are gravitational black holes. Finally, a striking relation between the potential energy stored in the universe and the total mass energy of the universe flows naturally from the field equations introduced here which explains an observation that Feynman referred to as the great mystery.