Well, I'm not really a Keirsey fan as I think his view of typology entirely misses the point Jung was trying to make and he's simply ascribing behavior and traits in relation to personality rather than actual cognitive processes. A lot of the people I think Keirsey would consider NTs (I'm a perfect example) would actually not be NTs in a Jungian sense because cognitively, they do not favor T and N as their two preferred ego functions. It's even arguable that we will never truly develop and differentiate an auxiliary beyond our dominant so according to Jung, what we really are are just being Ni dominant type, Fe dominant type and so on, making Keirsey's temperaments (and also Myers-Briggs type labels) rather useless. I've seen this myself with ISFPs who for example really seem to favor Fi and Si as their two preferred ego functions rather than Fi and Se, just like I've seen people type as ENFP because they favor Ne and Fe as their two dominant functions (e.g. [MENTION=17911]Maybe[/MENTION]) or INTJ with Ni and Ti (e.g. [MENTION=15372]flatlander[/MENTION]). The only thing that really groups these people together with people of similar type are their dominant function e.g. Ni. I've seen a person who is most definitely an INTJ (Ni-Ti) type as INFJ because his feeling is extraverted despite it being unconscious and because function wise, it fits the system of Ni-Fe-Ti-Se than INTJ being Ni-Te-Fi-Se. He falls on the wrong side of the T-F axis. Yet funnily enough, his feeling is still undeniably closer to Fi logic than Fe, but he is sensitive to the emotional atmosphere and moods in other people like Fe types are stereotyped to be. So what gives?
These people just have great difficulties trying to fit themselves into either system (aside Jung, since he only cares about your dominant and inferior function pair) and then there are people like me who express themselves almost more through their inferior than they do their dominant. I mean yes, in MBTI-land I'm undeniably an INTP. I'd score INTP on any MBTI test or close to (unless I'm extremely honest with myself which is difficult because I have a hard time telling if I truly make decisions based on feeling or thinking and it part depends on how the test delineates a preference towards thinking and feeling as I'm not a people-person so in this regard it's difficult for me to ever score remotely close to being an NF since I'm not a people-person) and my interests are closer to INTP interests (according to Keirsey) than an INFP despite that I'm ultimately a social scientist and I prefer humanist subjects over the natural sciences. I for example know a person who was an ENTJ according to Jung (Te-dominant, preference towards intuition as auxiliary over sensation) but typed as MBTI INTP because he is socially introverted and disorganized rather than stereotypically structured as many ENTJs are described to be.
As an example, I'm actually a Jungian NF (my cognitive dominant function is Fi) and I'm an atheist but with great interest in religion. Most of all though, I see strong overlaps between Keirsey's types and enneagram. I for example think that it would be unlikely for many 5s to be religious (5 descriptions overlap a lot with the INTx types) because the belief in an omniscient and omnipotent deity (let's define god this way for simplicity's sake) would seem too urealistic for the avaricious 5-mind who themselves in a way would in fact desire godhood status through the achievement of omniscience. I think many 5s would struggle with the belief in god simply because on the one hand, the 5 mind would want there to be something more to this life and universe as a way to provide meaning since the 5 ultimately believes that our existences are meaningless, but on the other hand accepting god would mean that we accept that this all there is to know. God is the answer, and to the avaricious mind, I am not sure such a conclusion would feel satisfying. Not because I'm saying that a 5 cannot be religious but I find that it is more likely for the 5 to try to unveil the mysteries of the universe in order to connect to god (can think of many movies with this theme e.g. 2001: A Space Odyssey, Pi, Altered States...). If a belief in god exists, I think the 5 would desire to know if there's something more than god.
Similarly, I see how a lot of Pe dominant types easily mistake themselves as 7s because Keirsey tends to stereotype Ne doms to be similar to 7s. Indeed, if you even study the psychobabble of 7s they seem to superficially think like Ne types do even if they really are Se types or something else entirely. Most of all though, I think it is relevant to ask why someone would choose to be religious or not as the answer to that question is more likely to indicate a person's type than whether they are religious or not. People can ultimately provide a wide variety of reasons why they would desire to be (dis)believers, and hearing these reasons reflect type much better overall since it reflects our cognitive thought processes.