as some Byzantine saint said:
If we ignore an image of christ, it is as if you are ignoring he was incarnated himself.
Christians don't believe God dwells in artwork or a wooden cross. And despize Idolatry as much as Muslims. These are used for remembrance and have no theological context whatsoever.
On the other hand, if you don't pray facing the kaaba, then Allah doesn't see you praying. Wich gives the kaaba a theological value and thus a attribute of Allah, wich resemblances more paganism then Da Vinci's last supper, or Michelangelo's Sistine's chapel. To think that the kaaba was used prior to muhammed as a means to praise a pagan God, makes you think, doesn't it?