But, wouldn't that number be kind of meaningless unless you made a survey to find out WHY they believe?
Well it shows that despite being biologists, physicists and mathematicians (i.e. fairly intelligent) a significant number still believe in a god.
That really doesn't show anything, though. IFF they believe BECAUSE of what they know about biology (complexity, for example), then that's a significant number. But they may instead believe as an emotional attachment to the religion their family taught, kept completely isolated from their intellectual accomplishments. I now a number of smart people who believe. They just refuse to apply their critical thinking skills to religious claims.
Kind of like the kid who is skeptical of what the teacher says, sneers at the claims of commercials, but believes EVERYTHING his favorite sports athlete says.
Perhaps a more enlightening question for these scientists is 'Does God factor into
your experiments and results?'.
That's actually something we can measure pretty easily - by searching for scientific papers that mention the role of god(s) in the methods, results, or conclusions.
And we find almost no mention of god(s) in the hard sciences. None.
When you drill down into this odd discrepancy - 40% of scientists believe in god(s), but only a fraction of a percent mention them in their published work - you will find that they believe in god(s) influencing the parts of reality that they haven't themselves studied in any great detail, but that they understand that god(s) are not relevant to their particular field.
Stepping back, we see that knowing about something in detail is
for all fields of science adequate to eliminate god(s) as a factor.
In other words, scientists, like everyone else, believe in god(s) only when they haven't yet studied in detail the phenomena that they are attributing to the supernatural.
A physicist may believe that god(s) are needed to explain the diversity of life, while a biologist thinks god(s) are needed to explain quantum weirdness. But almost never the other way around.
The more a person knows about ANY subject, the less likely they are to believe that god is a factor in that subject area - but as nobody knows all of science, plenty of scientists believe in god(s) that influence the bits of reality outside of their own purview.