Koran SURA IX (9.5)

"And when the sacred months are passed, kill those who join other gods with God wherever ye shall find them; and seize them, besiege them, and lay wait for them with every kind of ambush: but if they shall convert, and observe prayer, and pay the obligatory alms, then let them go their way, for God is Gracious, Merciful."

Mohamed calls Christians, those who join other gods with God. He calls them this, because Christians believe in The Blessed Trinity. Here, Mohamed clearly says, kill Christians, unless they convert and become Moslems.