Science and faith. These are two different mindsets. So different that they are fundamentally incompatible.
The methodology of science is based on careful analysis of verifiable observation. Scientists subject their own ideas to repeated checks to uncover flaws and expose their own errors. Scientists even invite their peers to go through their work to find such mistakes, which is potentially humiliating but necessary to avoid the effects of enthusiasm for an idea overstepping what is warranted by the evidence.
Faith on the other hand is defined by very different characteristics. Faith doesn't require evidence or observation. Faith is considered to be strongest in the absence of proof. In fact, faith can require turning away from evidence. Faith is choosing to believe based on what is wanted to be true, not on what is or is not actually observed.
Science simply cannot incorporate such wishful thinking, because the scientific method requires evidence and rationality at every step. It is a way of analyzing reality wholly dependent on evidence based reason. Such observation of the natural universe cannot incorporate faith directly nor substitute faith for any of its processes and remain intellectually honest.
Now that isn't to say that a productive, respected scientist cannot also have faith in the supernatural. Dr. Ken Miller is a practicing Catholic. He is also a well respected biologist and outspoken opponent of intelligent design creationism. I have great respect for Dr. Miller and other scientists like him. I even respect their right to believe in unfounded, supernatural, faith driven ideologies. But any such scientist must take pains to set aside religious faith when doing science, switching from one mode of thinking to another in order to consider only the naturalistic evidence. They cannot substitute a faith-based explanation no matter how tempting.
History shows us that sometimes even great scientists fail in that. But what we remember most aren't their scientific failures, but their successes. The great work of long dead natural philosophers and astronomers is valued for providing insights into understanding the universe in measurable, verifiable ways. Those insights were gained through vigilant observation under the care of brilliant, rational minds. Or at least they remained rational about their now famous research, even if in other ways their minds were polluted by nonsense, like Newton and his alchemy.
I want to emphasize that I'm not suggesting that scientists must be atheists. I know that some scientists will learn about the natural world and chose to interpret the meaning of that through their religious faith. But that is an additional, personal conviction of theirs that isn't directly warranted by the evidence. As such it fails to withstand Occam's Razor, isn't part of their scientific work, and represents a necessary switch from one type of thinking to another – because the mindsets of faith and of science are incompatible ways of determining what to believe about reality.