Actually, being a theist *is* an advantage in scientific inquiry. Fully developed, it is the realization of ultimate personhood assumed necessarily to be a logically referred-to mind-related system which necessarily influences all finite minds regardless of their views or the subject or nature of their inquiry, including the assumptions of science generally as well as empirical research specifically.
Cognitive propriety depends on an already-existing mind structure as guiding backdrop of conscious awareness, not just some independent or asietic cognitive ether of supervisory assumptions. Assumptions don't exist in the absence of mind. And an operating mind structure is a mind, by the very fact of its operations.
Theism produces a far greater purpose, and therefore motivation, since it's universal, necessary, and assumes a God-mind that guarantees an ultimate enduring significance and reliability to all inquiry, science-related or not. Ethics and morality take on a greater meaning and significance because of the existence of God. Reality is not just the universality of causal law and matter in motion, although universal causality is a prior condition for the possibility of finite moral activity.
The incentive of thought and life is limitless with theism, because everlasting significance and meaning are possible only if God exists. Oh, and by the way, they're also necessary.
That doesn't mean that an atheist's commitment or integrity etc. cannot equal the theist. It can and sometimes exceeds that of many theists (as in the case of some personal longtime friends who are atheist). But theism has certain motivational, ennobling, and visionary features that an atheist perspective simply does not have, although for many atheists it either does not need them or else already has them in somewhat analogous---although still not strictly equivalent---senses.