In this 3rd paper of a triptych in quantum theory, a mathematical description ab initio of gravitational field theory is presented. In this reconciliation description, quantum physics and classical general relativity (GR) merge seamlessly — instead of deviations from general relativity, the treatment results in identical (photon and massive Higgs boson coupled energy) trajectory curvatures in gravitational fields, however with 3 deviating conclusions regarding (naked) singularities, spacetime-curvature and graviton i.e. deviating from predicted by the Einstein tensor metrics of GR. The fundamental gravitation-potential treatment of the field description is developed in the complex Hilbert space. The gravity field then is mathematically identified by the causal relation between two vector-fields in convolution and emerges as scalar field, evolving pre-determined in space from the moment of mass creation i.e. the symmetry breaking. The gravitational field-theory eventually evolves in spacetime curvature, emerging as geodesic-trajectory curvature by energy objects in the spatial field of a gravitation source. In the field, the trajectories of objects are being determined only by the principle of least action (LaGrange, Feynman).