More spiritualism will only take us further away from world peace. Because spiritualism is usually guided by a set of guidelines which a person 'should' follow, and are more or less absolute which little room for deviation. Being less reliant of what one does not make on their own may very well be a path to personally finding answers; but spiritualism is a horrible way to go about it if solving problems and resolving conflicts is the real goal.

This is because there won't be only one form of spiritualism; like there are many currently, many more may pop up in the future. And when there is even a slight hint of peacefulness, each and every one of these subtly, usually passive aggressively get others to join them while simultaneously being extremely suspicious of the other groups doing the same. This is the best case, usually it just leads to ugly hatred, eventually.

An example of how it will take us away from world peace? As you put forth the reason yourself. People's 'sins'. That is very aggressive, passively. In the end, disagreement with a person's already made conclusion of 'sin' can only lead to argument which does not solve any real purpose related to peace, and making such a conclusion only incites disagreement from many who are directly accused as well as those who aren't but recognise how it is an action which will only destroy peace.