OK, I gotta jump in here, even against my better judgement.
Baptists, Lutherans, and Methodists do not necessarily disagree over anything, any more than we might with members of our own church. It’s just that not everyone likes the same style of worship or polity.
Now before anyone jumps down my throat, of course I realize that this is an extremely idealistic view, but it is the theory behind many denominations. The founders of United Methodism, Disciples of Christ, United Churches of Christ, amoung others never thought that other denominations were wrong, only that they had developed specific methods (hence, in one case, Methodists) of helping people follow Christ.
Furthermore, although most Christians believe that the Holy Spirit has helped (and continues to help) guide tradition, even pre-Vatican II Catholicism defined only a small part of their doctrine as the garaunteed product of divine inspiration. In other words, the Spirit is consistant, but doesn’t dictate every line in the church discipline. The teachings that different denominations do disagree on are pretty much agreed by most to be non-essential, even though one may feel very strongly about them. Of course there are a few assholes, and even entire denominations of assholes who think that they alone are loved by God, and everyone else can (and will) go to hell, but these are a much smaller minority than their vocalism makes them seem.
As for graven images, Obbie’s ignorance about these things, rosary beads in particular, indicates that he’s either had absolutly no contact with real Christians, or else was raised Catholic ;). None of the things you mentioned, Obbie, are worshipped by anyone, although Catholics and Orthodox may use rosary beads to help count their prayers, or those and any number of other things to help them focus on God while praying.
As for saints, well, I’m not Catholic, but there is this pretty universal doctrine called the Communion of the Saints, which says that all believers are part of a common community united by their faith. Since for some, all includes past, as well as present, they pray to saints for the same reason you talk to your priest and other churchgoers–they’re friends who are there to help you in matters of faith.