Allaah سبحانه و تعالى states,
When a Muslim reads the Qur'aan he must realise that everything it states is true. No matter what the topic might be, what Allaah سبحانه و تعالى says about it is the truth, regardless of whether it be something related to the unseen, the Hereafter, history, natural law, social law or any other subject. It is all true, coming from the Lord of the Worlds, and no truth can possibly contradict it.
This is an important aspect because sometimes someone may read a passage in the Qur'aan that 'seems' to go against the reality around him. This might make the person question or doubt the Qur'aan. But for the reader who realises that nothing in reality can go against the Qur'aan, this kind of event just opens his eyes. He realises, for example, that the Qur'aan is laying down some general law and there is some reason or precondition that is not being met that is keeping that law from being implemented. This will make him study the principles of the Quranic verse in greater detail, in light of other verses and ahaadeeth, to see what it is exactly that Allaah سبحانه و تعالى is describing. Or it will make him study what is happening in greater detail, going beyond the superficial level to find the true cause for the apparent - and only apparent - contradiction between what the Qur'aan states and what is happening in front of him.
For example, some question why there are so many Muslims in this world yet they are in such a humbled and defeated state. They argue that, in the Qur'aan, Allaah سبحانه و تعالى promises to help the believers yet this help and victory from Allaah سبحانه و تعالى does not seem to be coming about. This kind of argument can only come from someone who does not have complete confidence that everything that Allaah سبحانه و تعالى says in the Qur'aan is true or from someone who does not realise the intricacies of the principles stated in the Qur'aan.
Allaah سبحانه و تعالى promises to test the believers, to have them demonstrate their faith and willingness to sacrifice for Allaah's سبحانه و تعالى sake, before Allaah سبحانه و تعالى grants them victory.  Allaah سبحانه و تعالى states in Sooratul-'Ankaboot,
Furthermore, there is the question of whom Allaah سبحانه و تعالى promises to give victory and aid. Allaah سبحانه و تعالى says,
(Soorah Muhammad, 47:7)
One may ask how many Muslims today are really striving for the sake of Allaah سبحانه و تعالى and are, therefore, deserving of Allaah's سبحانه و تعالى support and victory. The answer to that question will demonstrate that Allaah's سبحانه و تعالى promise of giving the believers victory is true yet the Muslims are not fulfilling the conditions needed to earn victory and succor from Allaah سبحانه و تعالى.
When the astute and alert reader of the Qur'aan notices this apparent contradiction between reality and what the Qur'aan says, he is led to study the Qur'aan more deeply to understand what the Qur'aan is really saying. Hence, he ends up with a more complete and stronger understanding of the Qur'aan than the reader who doubts such passages or the one who does not even bother to notice such apparent contradictions.
Sometimes the apparent contradiction is because the reader does not realise the reality of what is happening around him. With respect to the situation of the Jews in occupied Palestine, one could argue that this seems to go against the clear teachings of the Qur'aan found in the verse,
(Soorah Aal 'Imraan, 3:112)
Actually the rest of this verse explains why there could be exceptions to this law:
(Soorah Aal 'Imraan, 3:112)
This is exactly what is happening today. If it were not for the billions of dollars of aid that the Jews receive from their allies in the West and others, they would, it seems clear, collapse. 
When the reader approaches the Qur'aan in this manner - knowing that what it says is true and that reality must follow it - he has a completely different awareness and understanding of the Qur'aan than the reader who does not give this concept much thought. The first reader not only knows that what the Qur'aan says is true but he also realises that what it states must be happening in the world around him. Hence, he understands what is happening around him and acts accordingly based on this deep understanding of the Qur'aan.
In addition, the believers must have confidence in themselves and in their religion in the sense that they believe that the remedy for any problem they face, modern or old, can be found in the guidance of Allaah. 
This attitude can be found in the Muslim who truly believes that everything the Qur'aan says is true and any contradictory way of life is falsehood. In reality, some Muslims, especially in the past few centuries, have "given up" on the teachings of the Qur'aan and have looked for alternative sources to find the best way to live in today's world. They still believe in the Qur'aan at one level but they fail to believe in it completely, in the sense that everything it says is true and will always be true, no matter what changes occur in the world.
Finally, it must be pointed out that this approach to the Qur'aan is essential for a believer. He is not free to doubt any verse or teaching of the Qur'aan because doubt or scepticism concerning any verse is tantamount to heresy and disbelief. It means that the person is not really certain that the Qur'aan is from Allaah سبحانه و تعالى; this is completely unacceptable. Either the person knows with certainty that the Qur'aan is the truth from Allaah سبحانه و تعالى, as is often stated in the Qur'aan, or, in fact, he is not a true believer. Similarly, the person does not have the right to believe in what he likes of the Qur'aan and disregard what he doubts or dislikes of the Qur'aan. Allaah سبحانه و تعالى says,
The believer must exert himself to see the truth of any Quranic passage if it is dealing with something he experiences and sees in this life. This will bring him closer to the Qur'aan and increase his correct understanding and application of the Qur'aan.