Quranic verses that dictate beheading Kaffirs:

5:33-“The punishment of those who wage war against Allah and His Messenger, and strive with might and main for mischief through the land is: execution (by beheading), or crucifixion, or the cutting off of hands and feet from opposite sides, or exile from the land: that is their disgrace in this world, and a heavy punishment is theirs in the Hereafter;” 

8:12- “I will instill terror into the hearts of the unbelievers: smite ye above their necks and smite all their finger-tips off.” 

47:4-  “Therefore, when ye meet the Unbelievers (in fight),  strike off their heads;  at length; then when you have made wide Slaughter among them, carefully tie up the remaining captives”: thereafter (is the time for) either generosity or ransom: Until the war lays down its burdens.” 

9:123:  “Oh ye who believe! Murder those of the disbelievers and let them find harshness in you.”

2:191-  “Kill them wherever you find them, and drive them out from wherever they drove you out.”

5: 45--  “We ordained therein for them: “Life for life, eye for eye, nose for nose, ear for ear. Tooth for tooth, and wounds equal for equal.”

2:193- “Fight them on until there is no more tumult and religion becomes that of Allah”

9:29-  "Fight those who do not believe in God and the last day... and fight People of the Book, (Christian and Jews) who do not accept the religion of truth (Islam) until they pay tribute (Zizziya tax) by hand, being inferior.”

8:17—It is not ye who Slew them; it is God; when thou threwest a handful of dust, it was not Thy act, but God’s…..” (Allah is a real merciful indeed!)