I'm not convinced that Einstein did this. For one thing, it appears from all accounts that he was a man of deep personal humility which accords with his constant reference to the awesome, not-humanly-fathomable mystery that lies at the root of the Universe. It doesn't square that he, by all reports a scrupulously honest man, would be inclined to make judgments on the basis of personal pride.
Whatever the case, I don't think Einstein was either a positivist materialist, or an idealist pantheist. I have no handy label for him.
I don't have a label for Einstein either.
And I strongly agree that his humility comes through his many quotes - and when he acted pridefully concerning the cosmological constant, he confessed it and repented openly. If he were not humble at the root, he couldn't have.
I do find it particularly illuminating that the two most influential physicists of all time - Newton and Einstein - both clearly recognized that God IS even though their profession of Who He IS was woefully uninformed.