I am reading "Einstein, a life", by Denis Brian. The book is remarkable--a two decade long labor of great love and reading. Quoted in the book is a dinner conversation where Einstein is asked about his religion by someone at the dinner:
"What?" exclaimed Kerr. "It isn't possible! I must ask him right away. Professor! I hear that you are supposed to be deeply religious?"
Calmly and with great dignity, Einstein replied, "Yes, you can call it that. Try and penetrate with our limited means the secrets of nature and you will find that, behind all the discernible concatenations, there remains something subtle, intangible and inexplicable. Veneration for this force beyond anything that we comprehend is my religion. To that extent I am, in point of fact, religious."
Denis Brian remarks that this is 'arguably the best explanation Einstein gave of his religious atitude'.