How to approach syncretism?

In the missiological sphere it is noticeable that it is a theme that produces endless debates seeking ways on how to approach it.  The question is: What to do with a syncretistic church? What attitude to take when this syncretistic church is the only one, or the most active, evangelical church in the region, people group or country? Traditionally the investment in the teaching of the Word and the attempt to train mature leaders has been the solution proposed in this kind of situations.  Personally, I believe that we must treat the Christian involved in syncretism in the same way as an unbeliever. In other words, seek to keep him near, attracted by what he knows or wants to know of the Gospel, and teach him the Word.  It is certain, however, that to re-evangelize a syncretistic church is a harder task than to plant a new church.