There are different ways for the individual to be religious, different modes of the religious life. [...] One categorization that is very influentional distinguishes between extrinsic and intrinsic ways of being religious. Persons with an extrinsic religion tend to use their religion for their own ends. Religion is thus instrumental and utilitarian. Thus, for example, such persons may use religion to provide security, solace, or self-advancement. Persons with an intrinsic religion, by contrast, have their religion as an end in itself. They attempt to internalize the beliefs and prescriptions of their religion. [...]
To this, a third mode of religious life has been added by some psychologists, the quest mode. This is characterized by persons who are open-ended and questioning in their approaches to religion. They resist clear-cut tidy answers to the existential questions trouble human beings. [...]
Various studies have been done assessing these three ways of being religious against both individual factors, such as mental health, and social factors, such as freedom from prejudice. The results of this research are complex and some of them are contrary to what one might expect. Extrinsic religion performed poorly in all areas. Individuals with extrinsic religion have poorer results on mental health, are more prejudiced, and are less likely to help others. Taking the mental health of the individual as one's criterion, intrinsic religion scores best of the three types in the various factors that have been eliminated. If one examines what most religious consider to be good relationships with others, however, one finds that individuals with intrinsic religion perform well only in circumstances where they are promoting a positive self-image. When measured by more subtle, covert techniques, they are also prejudiced, they only help others when there is minimal inconvenience to themselves and their help in such circumstances is likely to be only poorly related to the needs of the other person. In other words, it was found that their actions were motivated more by a desire to present themselves as good, caring people than by a concern for others. Individuals with the quest type of religion were found to be less prejudiced than others, even when this was measured covertly. They were not particularly more motivated to be helpful than the other groups but when they did help, their assitance was more closely related to the needs of the person bein helped.
(P. 163 - 165.)
It would be interesting to know how well non-religious people, and especially Secular Humanists, would do in an experiment of this kind. My guess is that non-thinking, non-religious people (such people do exist) would be no better than people on average. But one would expect thinking individuals, such as most who identify themselves as Secular Humanists, would do at least as well as those of quest type of religious people. Of course, thinking people are on a quest, so perhaps they were included in the experiment. I will have to look for more information about this.