Christianity sees non-believers as lost sheep subject to redemption through repentance and a simple profession of faith in Christ as savior. ISLAM (which is Arabic for submission) teaches that non-Muslims must be converted to Islam and, if they refuse to submit, they have no redeemable value - they are infadels. Islam teaches that it is permissible to shed the blood of infadels.
Dr. M. Khan the translator of Sahih al-Bukhari into English, had this to say in the introduction to his translation:
"Allah revealed in Sura Bara'at (Repentance, IX) the order to discard (all) obligations (covenants, etc), and commanded the Muslims to fight against all the Pagans as well as against the people of the Scriptures (Jews and Christians) if they do not embrace Islam, till they pay the Jizia (a tax levied on the Jews and Christians) with willing submission and feel themselves subdued (as it is revealed in 9:29).
Al-Ghazali (died AH 505, that is AD 1127) who earned the title "hoggat al-Islam, meaning rock of Islam", some five centuries after the time of Mohammad, is not apologetic in stressing the use of force in the preservation and progress of Islam:
"After the death of Mohammad, the man of the miracle [the Qur'an] and the apostle of truth and the companions, fearing the weakening of Islam, the decrease of the number of its followers, and the return of masses to their previous infidelity, saw that holy war and invading other countries for the sake of Allah, smashing the faces of the infidels with the sword and making people enter the religion of Allah as the most worthy of all tasks and better than all sciences."