Why people decline in spite of bearing the Quran and believing in Mohammed:
This is the general program: whenever people (and individual) become devoted to God alone and believing in all the apostles including the last apostle of his time --> people will be dignified and powerful;
while if they associate (Jesus, saints, rabbis, imams) and others with God --> then God will be against them (whether individuals or communities).
This is very obvious
in many ayat of the Quran, and
in the Book of Levites chapter 26.
So now, we see the Islamic countries in hard circumstances: not because of the Quran, but because of their association with God, and He is temporarily against them.
In Egypt and Iraq: for example: the ignorance about the essential part of the Islam:
the devotion to God alone: this is opposed and contradicted:
Everywhere the "maqam" and the shrines of the imams and their sons and the sheikhs are prevalent: people go to such shrines to ask their needs from these righteous people and to swear by them and ask them for help; while such righteous people died and went to Paradise: and when they were alive they could not answer the prayer neither could they after death grant people their needs.
Monotheism Is the Way of Success
An Hour with Ghosts
[About the monotheism in the Bible]
An Hour with Ghosts
So this is why, the enemy of Muslims captured their homecountries; just how Nabuchodonsor captured Palestine in the past and enslaved the Jews inspite of that they had the Torah with them and the prophets were among them (while they did not listen to them.)
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http://www.quran-ayat.com/conflicts/english2.htm#Their_Rebellion_against_Their_Prophet_>