Actually..... it isn't. It's pretty damn complicated and caused the entire Iconoclast Schism in the eastern church. The issue revolves around the idea of an image being the object of worship or even veneration. The Catholic church is loaded with relics. Indeed, a holy relic must be present in a Catholic high altar in order for it to function as an altar. Monstrances are used to worship the Eucharist (because of the Catholic belief of transubstantiation). The Protestant churches even rejected the crucifix on the grounds that they believe not in the sacrifice of Christ so much as in the resurrection of Christ. To them, a simple cross symbolizes the risen Christ.
Once again, much of this is perspective of the time in which Reformation occurred. Luther and his followers truly worried that people were worshiping graven images rather than using them as reminders. They found the worship of the Eucharist to be abhorrent because they rejected the idea of transubstantiation. To this day, Protestant churches which hold communion services do so with no specific sanctity shown to the bread or wine. To them, communion is a reminder of the Last Supper, not a sacrament. Protestants tossed out all the saints, all the saints relics, all the trappings of glamor which, they believed, distracted worshipers from focusing on God.
The basis of this difference is in the Protestant idea that worshipers do not require an intercessor to communicate with God. Catholics do. The Catholic faith is founded in the idea that the faithful can only come to God via the church. The Protestants, not needing any intercession, jettisoned everything except the most basic trappings of faith. They didn't need to implore saints for help, they didn't need Mary, they didn't need any sacrament beyond baptism, and they didn't even need clergy!
So if they believe in a risen Christ, then a statue of Jesus would be superfluous and, in the minds of some, even blasphemous. Protestants do not mind the symbology of the Christian faith. Frequent decorations include fish, doves, open Bibles, simple crosses, candles, oil lamps, and Old Testament items like Jacob's Ladder, the Tree of Life, rainbows, and loaves of bread.
Protestants haven't entirely escaped the Augustinian ideal however. Their churches are largely modeled after the Gothic style and in the wealthier churches you'd be hard pressed to tell the difference from a Catholic church as the layouts are very similar. Some Protestants are still big on stained glass but the subject matter is more remotely allegorical. You'll see scenes from the Book of Ruth or The Tree of Life or the parables, not figures of Jesus. You might run into an apostle, but that's rare.
The corollary is that you will know who will be saved and who will not by God's earthly favors toward a person. You cannot be certain who will go to heaven, but you can have a pretty good idea. Good works are wasted on people who are clearly not among the elect.
This concept, which spurred a whole debate on predestination verus free will all over theological circles and largely caused the Calvinist breakaway, remains at the heart of the Calvinist TULIP (those things necessary for salvation) adopted by the Synod of Dordt in 1619:
Therefore, it doesn't matter how many good works you do to try to bring someone to salvation. If they're not on the list, or worse, if you're not on the list, then you're fucked and there's nothing you can do about it. The key is that you don't know who will be saved and who will not. Like I said, you can get a good idea, but you'll never be 100% certain. How piously you live will tend to indicate whether you're among the elect, but even then you'll never be certain. This also means that if, somehow, you knew you were among the elect, a life of murderous debauchery and evil wouldn't make a difference either. You'll still go to heaven because you've been predestined to do so.
They've also given us great continuity and a sense of grandeur we wouldn't otherwise have.
