It's not complicated, except for our overpaid intellectual news media betters and the punditocracy.

For example, Huffington Post contributor Carol Kuruvilla informs us that the phrase is used in Muslim prayers and affirms the supremacy of God.  She even points out that American Christians use it, though in English.  Her main point: It's harmless.

All this is true, except the misleading statement about Christians.  The problem with her analysis is that it overlooks an additional reason for its use: warfare.

It's in the hadith.  In this one, Khaibar (or Khaybar) was a Jewish settlement.

Narrated 'Abdul 'Aziz: Anas said, 'When Allah's Apostle invaded Khaibar, we offered the Fajr prayer there yearly in the morning) when it was still dark. The Prophet rode and Abu Talha rode too and I was riding behind Abu Talha. The Prophet passed through the lane of Khaibar quickly and my knee was touching the thigh of the Prophet . He uncovered his thigh and I saw the whiteness of the thigh of the Prophet. When he entered the town, he said, 'Allahu Akbar! Khaibar is ruined. Whenever we approach near a (hostile) nation (to fight) then evil will be the morning of those who have been warned.' He repeated this thrice. The people came out for their jobs and some of them said, 'Muhammad (has come).' (Some of our companions added, "With his army.") We conquered Khaibar, took the captives, and the booty was collected. (Bukhari 1, no. 367)

It's difficult to be clearer than that. Muhammad used the expression to instill terror in the Jews of Khaibar and to announce his arrival.  As the hadith says, he conquered the town (or it surrendered).  Ruin will be inflicted on the town or the nation that is warned of impending battle when the people hear "Allahu akbar!"  The rest of the hadith goes on to say Muhammad enslaved the most beautiful woman, manumitted her, and "married" her.

So yes, Muslims use the phrase during prayers, but terrorists also follow Muhammad's example.  One more reason why this man's religion must be left behind.

James Arlandson's website is Live as Free People, where he has posted Twenty-five reasons to leave Islam, Rescuing Noah's ark from the flood of science, and Christianity is fastest growing religion in world.