The simpler belief system wins.

Steven Dutch suggested that the simpler belief system wins.
The more convoluted it gets,-- the less people go for it. This seems to me to make sense. After all, in Rome when there was competition between Christianity and the Roman gods, the simplest thing was to go with Christianity. Later on there was much effort put into showing how Christianity is reasonable --or at least defensible by some of the greatest minds of the Middle Ages. Later on Luther's ideas were also on the side of making things simple. Sola Scriptura is certainly on the side of making things reasonable and simple.

So what weakens Christianity today--if you go by this argument of Steven Dutch -is that it got to be too convoluted.

You need not that things should be easy. You also do not need to water things down. But you do need the belief system should make sense and not be self contradictory. It also should make moral sense.

It should not demand things that are prima facie [on the face of it] not moral. [In its origin Christianity succeeded, not because it was easy but because it was hard and demanding.]

Some of the weak points are the Trinity. If you hold by Sola Scriptura, then that is one thing that would have to be let go of. Paul himself is another example of a weak link in the whole chain. The prime opponent  of Peter and James all of a sudden becomes an authority? That is like having Karl Marx give lectures on the benefits of Capitalism.

Some of the positive points are Anselm and Aquinas and Hegel. That is to simplify the belief system does not mean it has to be without depth. Just that it should not be convoluted.