'Science without religion is lame, religion without science is blind.'
So Einstein once wrote to explain his personal creed:
"A religious person is devout in the sense that he has no doubts about the  significance of those super-personal objects and goals which neither require nor are capable of rational foundation."

His was not a life of prayer and worship. Yet he lived by a deep faith--a faith not capable of rational foundation--that there are laws of Nature to be discovered. His lifelong pursuit was to discover them. His realism and his optimism are illuminated by his remark:

'Subtle is the Lord, but malicious He is not'
('Raffiniert ist der Herrgott aber boshaft ist er nicht.'.').
When asked by a colleague what he meant by that, he replied:
'Nature hides her secret because of her essential loftiness,
but not by means of ruse'
('Die Natur verbirgt ihr Geheimnis durch die Erhabenheit ihres Wesens, aber nicht durch List.').

=====

My personal Note on the above:

It's truly a miraculous experience, watching a baby grow from infancy to childhood - struggling to crawl, move on all fours, sit, stand, walk and speak to the mother. The instructions wired into the brain are first decoded and practiced repetitively by the infant before it learns the tricks to balance itself, stand, walk and speak. The nurturing mother watches, encouraging her child; but every step of the learning process has to be taken by the child itself.

A similar process is in operation when we learn to walk on the spiritual path. An urge to seek the mysterious spirit arises in our mind; we then have to unlearn the earlier urges and directives of the ego, and learn new ways to perceive, hear and experience the spirit. The Universal Mother, with great love and affection, watches patiently - confident that her child would overcome the initial hurdles as it did the physical ones as an infant and  triumphantly come to her ultimately. For, she has already provided the needed equipment and knowledge for this new experience.

We have to have faith in this belief. Reincarnating over many births, benefiting from past experiences, like the child tripping, falling and finally learning to stand and walk and take great strides upon this earth, we too will be ultimately successful in attaining to the goal of Sat-Chit-Ananda that is pure Bliss.

Einstein who said he experienced the mystifying forces in Nature, stated also that he did not believe in a personal God - the anthropomorphic God created by man, in the image of man, for the worldly benefit of man, a God that ruled like a disciplinarian, granting favours to those who conformed and punishing the rebels, the fictional God of the religions preached by the Priests supported by the earth's Rulers.

The Upanishads however, speak only of a Brahman, (in the neuter as तत् - It), omnipresent, in every atom of the Universe and beyond, living in each moment of time, past-present and future. Conceptualizing this huge, timeless dimensionless presence in a Rama or a Krishna helps the mind of the seeker in the same manner as a stroller helps the child to walk steadily and learn. Identifying totally with a personal God of one's choice in this manner, one advances spiritually by leaps and bounds. The personal God then becomes the Universal Presence, which is experienced in the silence of the mind and the Bliss in the heart. Sri Ramakrishna Paramahamsa experienced this Blissful presence of the Universal Mother in the idol of Kali that he worshipped.

Hinduism is an amalgam of a core theory with accompanying puranas, practices, rituals and superstitions.  Understanding its core truth is a process like reaching the kernel of a coconut - remove the adhering coverings of fibre, break the hard shell, pour the water and reach the pure white delicious kernel. Is it any wonder that those who do not practice it with faith, sincerity, steadfastness, devotion and detachment see only its outer coverings are turned away?

Einstein did not believe in a personal God since he felt that organized religion and its rituals were not effective in ensuring the practice of the core that they preached about morality and ethics. He summed up this ineffectiveness, and his disappointment, in forceful terms thus:

When considering the actual living conditions of present day civilized humanity from the standpoint of even the most elementary religious commands, one is bound to experience a feeling of deep and painful disappointment at what one sees. For, while religion prescribes brotherly love in the relations among the individuals and groups, the actual spectacle more resembles a battlefield than an orchestra. Everywhere, in economic as well as in political life, the guiding principle is one of ruthless striving for success at the expense of one's fellow men. This competitive spirit prevails even in school and, destroying all feelings of human fraternity and cooperation, conceives of achievement not as derived from the love for productive and thoughtful work, but as springing from personal ambition and fear of rejection.

The Vedantic portion of Hinduism lays emphasis on a personal, moral, ethical code of conduct. It however, goes further to analyse the root cause of humanity’s suffering and concludes that the powerful, over-riding ego nurtured in societal materialistic values is to blame. This analysis, which is contained in the Upanishads, leads to many recommendations for getting complete control of the mind, over-riding the ego and developing contact with Universal Consciousness. Perhaps, had Einstein been more familiar with the Upanishads, he might have conceded the validity of Upanishadic statements - which do not refer to a Personal God but only the Brahman (in the neuter) as the source that exists every where - timeless, in all things and beings - perhaps like his concept of Energy.

This Upanishadic concept of the Universe is not religious but philosophical. Realizing the practical needs of the 99% of humanity, Hinduism’s ancestors created Gods, mythologies, rules, regulations and rituals -- all of which served an intermediate purpose like a ladder. An advanced practitioner like an ascetic (sanyasi) has to step out of it and proceed further on his/her own in order to realize the Truth. The spiritual path is aptly compared to a razor's edge in Katha-Upanishad thus: 

क्षुरस्य धारा निशिता दुरत्यया  

दुर्गं पथस्तत् कवयो वदन्ति 

kṣurasya dhārā niśitā duratyayā  

durgaṁ pathastat kavayo vadanti

Hinduism thus provides a 2-tier system: an elementary stage in which you believe in a personal Deity of your choice and follow rules for personal ethics and morality, and an advanced stage when one is ready to leave behind ego-dictated pursuits for material goals to seek the higher goal of realizing Sat-Chit-Ananda with the assistance of a Guru.  The Guru of Hinduism is merely a guide and an adviser, not a priest with authority to control and guide his flock in accordance with a set of rules prescribed in a book. He is a realized saintly person who has himself understood and practiced the Upanishadic statements relating to the nature of Reality and therefore is able to give his disciple (sishya) guidance in the travel along the spiritual path which is difficult to tread beset with obstacles, as described in Kathopanishad:

==========================