Was the inquisition the wrong way to keep Christian community pure? Well, I don’t like the wording of the object of the question (“keep Christina community pure”. But I can’t come up with a better one, so I will live with it. I am just not for sure this is the right way to phrase the goal of the inquisition.
There are two parts to this: was it effective? And was the evil averted by the inquistion greater than any evils of the tools of the inquistion? (the main evil of the tool would be capital pubishment, as many other tools of the inquistion were not evil at all but quite just).
I can’t answer for sure the second question.
But the first seems to be a resounding yes. Let’s not even look at it from the standpoint of spiritual benefits to the population of keeping their religion pure. Lets look at it from a standpoint of avoiding greater tragedy of violence.
The inquisition was mainly implemented in Spain. Spain was never torn by large scale religious disputes and violence in its society until after the inquisition was abolished. This is rather unique in Europe.
Even though other European countries employed captial punishment as punishment for heresy; they did not avoid large scale inter-religious conflict and violence. The Irish wars of the late 16th century by Elizabeth or the 30 years wars in central Europe were particularly devestating to the population at large. And it should be noted that other countries (England and Calvin come to mind) used a more unhumane form of capital punishment than burning at the stake after death by garroting (the most common form used in Spain for heritics in the first century of the inquisition). So it likely was not only the threat of death in Spain that kept the religious disputes in check, but more probably the judifical techniques of the Inquisition itself that made just as much of a difference (which were unsurpassed for fairness and just treatment of the accused prior to conviction up until that time).
Germany is the best example of what happened in Europe. It is often thought that Charles V’s “Peace at Augsburg” was an early model of how to deal with religious conflict inside a country. But it did no good, the 30 years war in the 17th century was the most destructive war in European history until WWI.
You have the French example. Religious conflict happened over and over again in that country, always with very bloody and violent results.
This did NOT happen in Spain. So, only looking at the avoidance of large scale bloodshed by the population as the result, the Inquistion seems to have been a resounding success.
However, it is still fair to call into question if the “ends justified the means” with respect to the use of an capital punishment (and an objectively inhumane form of capital punishment regardless of the historical circumstances). On this part of the analysis, it is harder to arrive at an objective answer. But it seems to me the answer would be yes, it was the wrong way to keep a Christian community pure. I say this, because it appears to me, by contrasting enforcement of religious homogeneity throughout various countries at the time; the Spanish Inquisition stands out as being most effective and yet it only varied in means from other countries in its judicial procedures. So it seems objectively speaking, that the judicial means of the Inquisition coupled with a more humane punishment (perhaps loss of property and banishment) would have been just as effective.
So my answer to your overall question is “yes”:it was the wrong way to keep the Christian community pure. But it was effective and the Spanish were much closer to “getting it right” than ever being given credit for (even by apologists of the inquistion).
Note: before anyone responds with the legal seperation of the punishment by the state from the judicial inquisition itself, I am well aware of that. But an honest analysis of the question must combine the two facets into one. The end result from a societal standpoint was the combination of the two.