They would also have been amazed that they could go out on the street and pray without getting crucified; that they could build a permanent church and not improvise in a catacomb, effacing every trace after they were through; that they could dedicate their human talents in art and craftsmanship to produce something lasting and beautiful for God and, in doing all that, welcome Christ into their hearts and bodies.  I realize they would have been thunderstruck; I also think it is somewhat puerile to imagine that human beings don't aspire for something more beautiful and lasting as a testament to what they deem important.