A quote from The Crucified God by Jürgen Moltmann, one of the most important and profound books I have ever read.
"The symbol of the cross in the church points to the God who was crucified not between two candles on an altar, but between two thieves in the place of the skull, where the outcasts belong, outside the gates of the city. It does not invite thought, but a change of mind. It is a symbol which therefore leads out of the church and out of religious longing into the fellowship of the oppressed and abandoned. On the other hand, it is a symbol which calls the oppressed and godless into the church and through the church into the fellowship of the crucified God."