Salam Alaykum ...
In the name of God the Merciful: And We sent not before you except men to whom We revealed [Our message]. So ask the people of the message if you do not know. [16:43].
NO ONE CAN CHANGE ANY LETTER IN THE QUR'AN BUT HE CAN EXPLAIN IT !! CHANGING QURAN IS VERY HARD BECAUSE MANY MANY PEOPLE ALREADY MEMORIZED AND IT IS VERY HARD TO CHANGE IT... NO ONE IS ALOUD TO. many tried but didn't work

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Some Verses may be unclear to Muslims, so it needs Pope Equivalent, who is called Sheikh:
1. He knows the ruling with Yaren (absolute certainty) or Diahann (probability) through the tools of juristic reasoning.
2. He understands the question in full. In order to give the ruling, he must understand the question and the circumstances surrounding it completely.
This means that the inquirer asks the question in a clear and concise manner. He or she informs the Mufti of all the facts of the situation. This includes any details that are likely to be pertinent to the situation. This can include: age, occupation, specifics about the situation ? anything that could affect the guidance that the mufti may give.
3. He is able to pay full attention and is not hungry, sleepy, agitated, angry, or in need to answer the call of nature. Moreover, he cannot be experiencing pain, extreme illness, or any need immediate medical attention to relieve extreme pain or discomfort.
For the questioner, part of this means not annoying the mufti by asking him questions at times or situations that may be inconvenient for him, his family, or his health. Many times when a shaikh or ?alum comes to town and offers some time to spend with students or questioners at the masked, the students will not let him rest until he is to the point of absolute exhaustion and the signs of fatigue show on his face. The student should not wait outside every door they enter in hopes of ambushing them with questions, nor excessively inflate their email in boxes; rather, he or she should ask what time is best for them and approach them at that time. This is not only bad for the process of asking questions but it also shows a lack of care and respect for the health and well-being of scholars. Students should be open and sincere with scholars and treat them with utmost respect (without exaltation) but should also make sure not to burden them with excessive questions.
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But what I don;t understand, is that the Pope (Christianity) Switched the old testament so easily to a new one O.o ... that confused me .. No Offense