When people are eclectic and mix concepts from different thinkers, there is always a danger that they will end up combining contradicting ideas (I recently praised R. Baruch Simon for not doing this). Here is an example:
When confronting the problem of suffering and evil in the world, many turn to the idea that God intentionally hides his presence. The earliest Jewish source in which I can recall seeing this concept is the writings of R. Moshe Hayim Luzzatto (Ramhal). God's presence is intentionally somewhat hidden because, otherwise, His obvious presence would force us to believe in Him, thereby removing our free will.
On the other hand, when dealing with Creation or evolution, people argue that the "intelligent design" of the universe proves that it was created.
When confining the theories to different subjects, the contradiction is not always obvious. But when looked at comparatively, it is clear that these two worldviews are entirely incompatible. One could reconcile them by, for example, stating that "intelligent design" only implies a creator but does not prove it, thereby leaving room for free will. As we have seen in past posts, however, there are those who believe that one can and must actually prove God's existence, and not merely decide that it is the most likely alternative. To them, such a reconciliation is meaningless. If they adopt the Ramhal's view that God's presence is hidden to allow for free will, they are contradicting themselves.
This is the danger of eclecticism.
Using a Christian variant on the above ideas, Douglas Adams ably mocks such inconsistent thinkers in his The Hitchhiker's Guide to the Galaxy, p. 60:
Now it is such a bizarrely improbable coincidence that anything so mind-bogglingly useful could have evolved purely by chance that some thinkers have chosen to see it as a final and clinching proof of the nonexistence of God.
The argument goes something like this: "I refuse to prove that I exist," says God, "for proof denies faith, and without faith I am nothing."
"But," says Man, "the Babel fish is a dead giveaway, isn't it? It could not have evolved by chance. It proves you exist, so therefore, by your own arguments, you don't. QED."
"Oh dear," says God, "I hadn't thought of that," and promptly vanishes in a puff of logic.