An insider in religion can be described as somebody who is a full participant in his or her religion and is devoted in the faith and teachings of his religion. Conversely, an outsider is somebody who has an objective view on religion, does not participate and merely views himself as an impartial observer.
In addition to defining insider and outsider in the context of this question, we also must differentiate between what it is to understand and explain religion. To understand religion is to know and comprehend the aspects of it. However to explain it, requires a person to interpret his own understanding of religion and to be able to make clear the details of it.
Over the course of this essay, we will take the views of both insiders and outsiders, as being better equipped in regards understanding and explaining religion. We will look at advantages and disadvantages of both these positions. Of course it will not be possible to cover all aspects of this broad topic in this essay, however we will cover the main features which validate the argument. As Kim Knott puts it,
“we find ourselves considering the nature and limits of objectivity and subjectivity, ‘emic’ and ‘etic’ positions, ‘experience-near’ and ‘experience-distant’ concepts, empathy and critical analysis, the effect of personal standpoint and the process of reflexivity”(John Hinnells, 2005: 259).

Main Body
The notion that the religious insider is better equipped to understand and explain religion is fairly widespread. The thought behind this can be summarised as, because they have been devout to their religion, in most cases for all their lives, they have a familiarity and a certain feel for the religion that an outsider could never attain. Wilfred Cantwell Smith said on the matter,
“no statement about a religion is valid unless it can be acknowledged by that religions believers” (Ross Reat, Sept 1983: 460).
The above statement contends that the outsider cannot comprehend what it truly is to understand a certain religion because he simply cannot know what it means to have that belief. The fact that the outsider has no belief in the religion would imply that he is also a sceptic of it. In other words, if he believed, he would have joined.
Also the point can be made here that as outsiders of the religion, when they try to speak and gather information from insiders, they can often be met with the sense of being a threat. Insiders can conceivably withhold information and purposely not lead these outsiders towards the truth behind their religion because of this trepidation. Obviously this is a huge disadvantage for outsiders in trying to understand religion. In a study done in 1956 Festinger, Riecken and Schachter recognised this problem and decided the best way to contend with it was to,
“gain covert admittance to a group, and then observe the behaviour of its members from the inside” (Hinnells, 2005: 265).
This worked to some extent, but had a fatal flaw. As a result of immersing themselves in the group they found themselves,
“influencing those people they were supposed to be observing” (Hinnells, 2005: 265).
Also the reason why the insider has the advantage in understanding, is that he knows the language of the religion. There are vast amounts of terminology that are exclusive to each and every different religion. Obviously it is a huge advantage for the insider to be aware of the meaning and the proper use of these terms. However, whilst it is an advantage for insiders in understanding religion, consequently it can also be stated that this is a disadvantage when trying to explain religion. What is meant by this is, if an insider is using these insider words, expressions and terminologies in trying to explain their religion to an outsider, obviously a lot of it will simply not be understood.
In saying this we must look back to the outsider once again. An outsider is in a position where he is a lot more capable of explaining religion because he is not accustomed to the use of these insider words and terminologies. Thusly, he can speak in clear, straight forward terms when explaining it to fellow outsiders. However, just because he is more capable of explaining, does not necessarily mean he has sufficient understanding to do so.