The experimental test of the CHSH inequality confirms the quantum-mechanically predicted perfect correlation between two spatially separated photons. By interpreting the correlation non-locally as the so-called entanglement, Bell's theorem denies the existence of definite polarizations possessed by photons in the absence of measurement. The denial amounts to refuting Einstein's argument for defending his local-realist world view based on his separability principle and his ensemble interpretation of ψ-functions in the Einstein-Bohr debate on the conceptual foundations of quantum mechanics. This paper shows that Bell's theorem is incorrect and presents an explanation of the correlation based on Einstein's argument. The correlation is deterministic. A formal analysis supporting Einstein's explanation is also presented.