Einstein became an atheist in General Relativity.

In his old age, Einstein became an atheist in the religion he founded. He came to the conclusion that Relativity and Mathematical ‘physics’ in general were nonsense:

“All these fifty years of conscious brooding have brought me no nearer to the answer to the question, ‘What are light quanta?’ Nowadays every Tom, Dick and Harry thinks he knows it, but he is mistaken… I consider it quite possible that physics cannot be based on the field concept, i.e., on continuous structures. In that case, nothing remains of my entire castle in the air, gravitation theory included, [and of] the rest of modern physics.”

(letter to Besso, August 10, 1954) in A. Pais, Subtle is the Lord, p. 467

His disciples were so offended by Einstein’s change of heart that they isolated and ostracized him. As part of this process, they made Einstein a reluctant hero of General Relativity…

“I am generally regarded as a sort of petrified object, rendered blind and deaf by the years.”

(letter to Born, April 12, 1949) A. Pais, Subtle is the Lord, p. 462.

“I have become an obstinate heretic in the eyes of my colleagues…”

(letter to Besso, August 8, 1949) A. Pais, Subtle is the Lord, p. 462.

Einstein had realized in his latter years that the physical interpretations that Mathematical ‘physics’ offered for micro and macro phenomena were surrealistic and irrational.

Followers of Einstein usually are ignorant of his change of heart or downplay his ‘unfortunate’ latter-day conversion. Instead, they credit him for just about everything, including: black holes, gravity waves, and Big Bang in spite of the fact that Einstein wrote papers against each of these proposals:

Against black holes: On a Stationary System With Spherical Symmetry Consisting of Many Gravitating Masses (1939)

Against gravity waves: On Gravity Waves (1918)

Against Big Bang: On the cosmological problem of general relativity (1931)

Einstein also refused to believe or accept the surrealistic physical interpretations of Quantum Mechanics…

Against Quantum Mechanics: Can Quantum Mechanical description of Physical Reality be Considered Complete?

Stephen Hawking on Einstein & Black Holes

Chandrasekhar realized… that there is a limit to the repulsion that the exclusion principle can provide. The theory of relativity limits the maximum difference in the velocities of the matter particles in the star to the speed of light. This means that when the star got sufficiently dense, the repulsion caused by the exclusion principle would be less than the attraction of gravity. Chandrasekhar calculated that a cold star of more than about one and a half times the mass of the sun would not be able to support itself against its own gravity. (This mass is now known as the Chandrasekhar limit.)

This had serious implications for the ultimate fate of massive stars… Stars with masses above the Chandrasekhar limit… have a big problem when they come to the end of their fuel… what would happen if you added more mass to a white dwarf ‘or neutron star to take it over the limit? Would it collapse to infinite density?

Eddington was shocked by that implication, and he refused to believe Chandrasekhar’s result. Eddington thought it was simply not possible that a star could collapse to a point. This was the view of most scientists: Einstein himself wrote a paper in which he claimed that stars would not shrink to zero size. The hostility of other scientists, particularly Eddington, his former teacher and the leading authority on the structure of stars, persuaded Chandrasekhar to abandon this line of work and turn instead to other problems in astronomy, such as the motion of star clusters. However, when he was awarded the Nobel Prize in 1983, it was, at least in part, for his early work on the limiting mass of cold stars. Chandrasekhar had shown that the exclusion principle could not halt the collapse of a star more massive than the Chandrasekhar limit…

Stephen Hawking, A Brief History of Time, Chapter 6: Black Holes (1988)