The photo above is of a fresco found in a Roman Catholic Church in Chivay, Perú. I would pass through Chivay on my way from Arequipa to Cabanaconde where I would mount a mule to go to celebrate the Liturgy in Choclo. Choclo is an indigenous (Quechua) village in the Colca Canyon. However, if in Chivay I turned to the right instead of the left, I could reach the town of Tuti. If you are really interested, you can Google™ those towns, city, and village, and you can see where we lived (Arequipa), and through what places I traveled in indigenous ministry (Choco) many years ago.
That drawing reminds me of one of the missionary struggles that has to do with the difference between inculturation and syncretism. The line is not always easy to draw (pun intended). And, it does apply to some of the arguments that we have today in the First World. Look at the fresco. It is a fresco of the Apostle James the Greater, who began the evangelization of Spain.
How many of you believe that Saint James looked just like a Spanish caballero, long before they existed? This fresco is an example of inculturation. It is clearly not syncretism, because there is no mixture of religious beliefs. But, it is important that you note that it could be argued that it is an example of syncretism if one merely argued that any mixture between cultures is syncretism. In fact, that type of argument is the argument that is used by all too many of the critics of various traditions in modern Christianity.
That is, the type of argument is used that if anything in the “story” resembles, or comes from, the previous culture, then this is proof of syncretism, or proof that a previous part of the culture was somehow subsumed into the new religion and made to support the new religion. Thus, if you use “vestments” that resemble local wear at the time, you will be made fun of if you do not change the vestments to “current” wear. If you were to “make up” vestments, you would be made fun of.
Syncretism really does exist. Syncretism is an inappropriate mixture of the old and the new. Some anthropologists would claim that the mixture is never inappropriate, but that is the difference between an academic attitude and a non-academic attitude. An academic attitude is incredibly important. That is, we need to be able to describe the mixture of the old and the new in a dispassionate and neutral attitude.
But, we also need the non-dispassionate attitude. A non-dispassionate attitude asks the question about ultimate meanings. Ultimate meanings are important. It is only when one asks the question about ultimate meanings that one can differentiate between what is purely cultural and appropriate adaptation and what is inappropriate syncretism. But, that type of question comes from philosophy and not anthropology. This is why both a passionate and a dispassionate approach are so important.
Many of today’s modern scholars try to take the attitude that a dispassionate approach is the only appropriate one. But, they are incredibly wrong. The only appropriate approach is one that mixes a dispassionate approach with a passionate approach. The drawback to the dispassionate approach is that it is incapable of making a value judgment. That is, is something right or it is wrong. The drawback to a passionate approach (what is the ultimate meaning of this study) is that it sometimes misses the descriptive part of scholarly research.
=== MORE TO COME ===
 Well, as long as you ignore the fact that he was killed by Herod Aggrippa I at a time when the Church was not even reaching out in evangelism to the Roman Empire. Even the Catholic Encyclopedia lists this as a legend. But, sigh, I am Latino enough that I still claim our beloved Santiago. In Spanish, Saint James is called Santiago. It is probable that this is a conflation of the Latin word for Saint (Spanish comes from Latin, so Sancti) and Jacob (Iakobus). So Sancti Iakobus becomes Sancti Iakob then they merge and the k becomes the softer g sound and you get Santiago. The c and the b drop out because they are not really Spanish phonetics and you get Santiago.
Another possible derivation is from one of the dialects of Spanish that did not become the main dialect. There Iakobus does slowly become Tiago or Iago, and the derivation is much easier to see. Portuguese became its own language, but there he is, indeed, Tiago.