These are three of the areas which have caused me to wonder.
Mary - all the veneration of Mary, and doctrines that seem so similar to various goddesses of ancient time. Queen of Heaven, for example, Immaculate Conception. Assumption. Sinless life. Doesn't the Bible say "all have sinned and fallen short...."?
Transubstantiation - the teaching that bread and wine become the actual body and blood of Christ. Certain religions,such as Mithraism had somewhat similar ideas. Eucharistic adoration appears to be pushed again by the Church. Hm. Could this be where Christianity and paganism come very close to one another?
Saints - in reading it seems that at least some of the saints were 'baptized community heroes and heroines' that predated Christianity. The notion that they can somehow influence God when we pray to them for assistance has puzzled me. Like they are demigods and goddesses to have powers separate from God. I never understood, for example, how St. Anthony of Padua helps us find lost items. Etc. Seems that most of the women saints were virgins??? That strikes me as not Christian where family is so properly emphasized.
My favorite aspects of the Church are the comfort it provides believers, the ways in which it reaches out to those in need, the selfless service of priests and nuns, its schools and hospitals, and the gospel of love that is at its core. Doctrines that can serve as strait jackets for our minds are secondary. We are 'saved' by following the example of Christ as best we can, together with a simple faith in Him, rather than reciting creeds, receiving communion, etc. See Matt. 25:31ff again.
But God bless everybody - of every creed, color, culture and country. Let us make religion a bridge rather than a barrier.