Hm... I wonder how many biologists reject the theory of evolution in favor of creationism / intelligent design? Likewise for physicists, geologists, and astronomers for their respective theories...
None that will do any relevant work.
Many prominent figures were religious. Yet their body of work was independent.
To put it differently. God created world in 6 days 6000 years ago. For a believer, that is it. The fossils are not older, they do not study them because there is nothing to study. God placed those fossils in earth. Creatures do not evolve. They haven't changed since God created them 6000 years ago. There is nothing to study.
As such, whatever the degree they hold or job function they perform is just that - a label. They are not doing anything to challenge any beliefs at all. Not religious, not personal, not scientific. They might be working in a role associated with science, but they will not contribute anything to it. They will be performing what is ultimately menial work. Running experiments, writing articles, talking at conferences. That is no more the insight than eating lunch or going to work. All great scientists did this - but it's not what brought new discoveries.
Theory of evolution is not a religion. It is an observation proven through scientific method. It can be disproven through scientific method. It cannot be disproven by dogma. It may be ignored.
It is perfectly fine for a biologist to examine alternate hypothesis for origins of life. They are perfectly fine to claim "All life was created 6000 years ago" or "Life was created by Xenu" or "it's turtles all the way down".
If they make such a claim in their respective domain, they better present proof of hypothesis or an design an experiment to validate it. If they don't, their career is over. When cold fusion became all the rage, many promising and smart physicists destroyed their careers with a single publication. Not because it touched the topic, but because they made claims they could not substantiate. Putting their name on such claims destroyed their credibility.
The drive of a scientist is to challenge the existing knowledge, to provide further insight. Accepting dogmatic view of anything prevents such scientist from doing anything meaningful. It took much less for people to waste their careers on dead ends.
Whether or not life began 6000 years ago is a pissing match. Nobody cares. The true insight lies in how it began. If it was God - cool, let's find him. If it was chemistry 6 billion years ago - cool, let's get a petri dish and make our own life. If it was aliens - cool, let's call them back and tell them we're fine. If we're in matrix - cool, let's hack it and go to Zion.
Personal beliefs are not exclusive with that. Trying to justify them however is. Not because of a conspiracy, but simply because historically, all such beliefs have turned out to be a folly. Or maybe not - but none of the people that we know of today and to whom we attribute advances in knowledge exhibited any such traits. So it has not been disproven, it's the lack of proof.
Any relevant scientific discovery speaks for itself. And no matter how loud people yell to keep it quiet, it persists. No amount of book burning, personal attacks or other attempts to silence them ever worked. It happened to Newton and it took several years to correct it. Many discoveries (although mostly related to technology rather than science) have been incorrectly attributed to people who were first to sell them, but this is correcting itself as more knowledge becomes accessible (see history of computing, the 50s and earlier era).
At the end, one lifetime is too short for any true advance to occur. People who promote their agenda have completely different goals and merely use some popular topic to promote themselves, not the beliefs or topics they talk about.