I maintain that the cosmic religious feeling is the strongest and noblest motive for scientific research. Only those who realize the immense efforts and, above all, the devotion without which pioneer work in theoretical science cannot be achieved are able to grasp the strength of the emotion out of which alone such work, remote as it is from the immediate realities of life, can issue. What a deep conviction of the rationality of the universe and what a yearning to understand, were it but a feeble reflection of the mind revealed in this world, Kepler and Newton must have had to enable them to spend years of solitary labor in disentangling the principles of celestial mechanics!-Albert Einstein (source)
Very pretty prose, but pshaw! I say. That only shows is that cosmic religious feeling is a very pretty motive for scientific research, not that it is the strongest and noblest. By calling it the strongest and noblest, Einstein is basically insulting all other possible motives, and praising the one motive that he himself happens to hold.
I am aware that Einstein uses "religion" and "religious feeling" in idiosyncratic ways; however, regardless of what he means, he's still holding one particular motive above all others. Surely there is more than one respectable motive to do science. Just as there are many motives to go into law or medicine (two other disciplines that require immense effort and devotion).
If you're having trouble imagining any other motive to do science, a few examples are offered by modern scientist archetypes. The first one that comes to my mind is the cynical scientist archetype, greatly popularized in House, M.D. Dr. House's main motivation is the puzzle. He won't even take a case unless he thinks the medical puzzle is interesting enough. It's not so much about the truth, as it is about the challenge of figuring out the truth. This archetypical narrative certainly has its flaws, but I think it more closely reflects my own motivations than does the narrative painted by Einstein.
What about other archetypes, like the geeky engineer? Totally motivated by cool explosions, right? That sounds way more noble than whatever Einstein said.