I assume then that you would disagree with honeto's statement (Oct. 5, 7:18 p.m.): "... the prophet is His chosen person to lead mankind toward the right, till the end of time."  But you do believe that the Prophet's words in the Hadith remain authoritative for all time, don't you?

And so have innumerable imams and other leaders, but their explanations are not authoritative, i.e. they can be questioned, disputed or re-interpreted; nor are they universal.  In other words, they are not holy scripture.  More importantly, the hadiths go well beyond mere explanation.  They add all sorts of rules, penalties, interpretations and other details not found in the Quran.

Sign*Reader mentioned prayers as an example.  I'm eagerly awaiting his further comments on the subject, but I expect he is going to tell us all sorts of particular instructions in the hadith about how and when to pray.  What I'm saying is that any such instructions are not authoritative.  They do not come directly from Allah, and do not necessarily apply for all time.  There may have been particular reasons (cultural, historical, practical) why Muhammad recommended them.  We don't know.  What we do know is that if they are not included in the Quran, then they are not an essential part of Islam.

Yes, this is the Islamic view of Prophet's words, that it is authoritative for all time, not only during his times

Will you please tell us how did you come with this conclusion ?
The Prophet ( PBUH ) was ordered to deliver the message AND explain it

بِالْبَيِّنَاتِ وَالزُّبُرِ وَأَنزَلْنَا إِلَيْكَ الذِّكْرَ لِتُبَيِّنَ لِلنَّاسِ مَا نُزِّلَ إِلَيْهِمْ وَلَعَلَّهُمْ يَتَفَكَّرُونَ {44}

[16:44] With clear arguments and scriptures; and We have revealed to you the Reminder that you may make clear to men what has been revealed to them, and that haply they may reflect.
[Yusufali 16:44] ...... We have sent down to you the Reminder so that you may make clear to all people that has come down to them, so that they may reflect and be guided 

وَمَا أَنزَلْنَا عَلَيْكَ الْكِتَابَ إِلاَّ لِتُبَيِّنَ لَهُمُ الَّذِي اخْتَلَفُواْ فِيهِ وَهُدًى وَرَحْمَةً لِّقَوْمٍ يُؤْمِنُونَ {64}

[16:64]And so it is, We have sent down the Book to you, specifically to make clear to them about which they dispute. Thus it is indeed a guidance and mercy for a people who believe ( in divine revelation ) 

Necessary for what ? Faith, practices, financial dealings, or what ?

Qur'an demonstrates the principles of some and the details of others, and instructs us to follow the Prophet (PBUH) in application of all for He ( PBUH ) is the role model for how to apply the principles and orders in the Qur'an

For instance, Qur'an demonstrates the principles and details of faith, but doesn't demonstrate the details of practices like prayers , fasting, zakah ( charity )

In Islamic fiqh ( jurisdiction ) there's about 1.2 million points of discussion ( yes 1 million 200 thousand ), the sources for these points doesn't come only from the Qur'an, it' is the First source, but not the only one

This is why when sayeda Aisha was asked about the manners of the Prophet (PBUH) , her answer was , don't you read the Qur'an ? His manners was the Qur'an

True, which was never done
but Qur'an also ordered us to follow the Prophet (PBUH)

Correct,

Imam Malik has a famous saying that illustrates muslims believe in that, when he stood near the grave of Prophet Muhammad ( PBUH ) and said

We can take and reject from everyone, except for that who's in this grave

True as well, because they come from the Prophet ( PBUH ) whose sayings are guided from God whom instructed us to follow the Prophet ( PBUH )

The Qur'an doesn't come directly from God as well, it comes through Prophet Muhammad ( PBUH )

The Qur'an instructed us to follow him, and this is why his words became authoriative

There're numerous verses that instructs believers to obey the Prophet ( PBUH ) , these verses are authoritative and for all times and so the instructions in it are for all times

مَّنْ يُطِعِ الرَّسُولَ فَقَدْ أَطَاعَ اللّهَ وَمَن تَوَلَّى فَمَا أَرْسَلْنَاكَ عَلَيْهِمْ حَفِيظًا {80}
[ 4:80] Whoever obeys the Messenger, he indeed obeys Allah, and whoever turns back, so We have not sent you as a keeper over them.

فَلاَ وَرَبِّكَ لاَ يُؤْمِنُونَ حَتَّىَ يُحَكِّمُوكَ فِيمَا شَجَرَ بَيْنَهُمْ ثُمَّ لاَ يَجِدُواْ فِي أَنفُسِهِمْ حَرَجًا مِّمَّا قَضَيْتَ وَيُسَلِّمُواْ تَسْلِيمًا {65}

[4:65] But no, by the Lord, they can have no (real) Faith, until they make thee judge in all disputes between them, and find in their souls no resistance against Thy decisions, but accept them with the fullest conviction.

وَمَن يُطِعِ اللّهَ وَالرَّسُولَ فَأُوْلَـئِكَ مَعَ الَّذِينَ أَنْعَمَ اللّهُ عَلَيْهِم مِّنَ النَّبِيِّينَ وَالصِّدِّيقِينَ وَالشُّهَدَاء وَالصَّالِحِينَ وَحَسُنَ أُولَـئِكَ رَفِيقًا {69}
[Shakir 4:69] And whoever obeys God and the Messenger, these are with those upon whom Allah has bestowed favors from among the prophets and the truthful and the martyrs and the good, and a goodly company are they!

قُلْ إِن كُنتُمْ تُحِبُّونَ اللّهَ فَاتَّبِعُونِي يُحْبِبْكُمُ اللّهُ وَيَغْفِرْ لَكُمْ ذُنُوبَكُمْ وَاللّهُ غَفُورٌ رَّحِيمٌ {3:31}
[3:31]Say(O Muhammad, to mankind): If you love God, then follow me, God will love you and forgive you your faults, and God is Forgiving, Merciful

قُلْ أَطِيعُواْ اللّهَ وَالرَّسُولَ فإِن تَوَلَّوْاْ فَإِنَّ اللّهَ لاَ يُحِبُّ الْكَافِرِينَ {32}
 [3:32 Say: Obey God and the Messenger; but if they turn back, then surely God does not love the unbelievers.

قُلْ يَا أَيُّهَا النَّاسُ إِنِّي رَسُولُ اللّهِ إِلَيْكُمْ جَمِيعًا الَّذِي لَهُ مُلْكُ السَّمَاوَاتِ وَالأَرْضِ لا إِلَـهَ إِلاَّ هُوَ يُحْيِـي وَيُمِيتُ فَآمِنُواْ بِاللّهِ وَرَسُولِهِ النَّبِيِّ الأُمِّيِّ الَّذِي يُؤْمِنُ بِاللّهِ وَكَلِمَاتِهِ وَاتَّبِعُوهُ لَعَلَّكُمْ تَهْتَدُونَ {158}
[7:158] .... and follow him ( the Prophet )so that you may be guided."

وَأَطِيعُواْ اللّهَ وَالرَّسُولَ لَعَلَّكُمْ تُرْحَمُونَ {132}
[3:132] And obey God and the Messenger; that ye may obtain mercy.

If we follow what you're implying to, then here's something that we don't know, which you would consider unimportant, and not an essential part of Islam

We wouldn't know the details of each prayers, that Morning prayer ( subh ) is 2 rak'a while Noon prayer( zuhr ) is 4 ...etc.
We wouldn't know how to perform prayer, do we read Qur'an first then bow down , or the other way around, do we read Qur'an , or zikr or .. ?
Wouldn't know when we should break our fasting, is it immediately after sunset while there's light visible, or when it's totally dark
We wouldn't know how much money one should own before paying zakah, for how long, and how much is the zakah we should pay
We wouldn't know which month we perform hajj, how to perform it

The list goes on

Basicly Islam would me more of a spiritual practices, that's based on each individual preferences, not a religion that unites believers

This is probably what many people want Islam to be, but this is not the Islamic belief

The idea you're talking about is not new, it's almost 1300 years old, and has been refuted since then
Some people who call themselves the Qur'anist share some of the things you proposed, and their ideas have been refuted as well

It's worth noting that the Prophet ( PBUH ) warned us explicitly from doing just tha, He ( PBUH ) said :

It's close that a man leaning on his couch and when he's spoken to by my words he would say:

"what's between us and you is the book of God ( only ), what we find in it that's permissible ( halal ) we consider permissible and what we find in it forbidden ( haram ) we consider forbidden!"

For what the messenger of God made forbidden is the same as what God made forbidden

Narrated by Ibn Majja ( 12 ) and Al Darami ( 585 )

So, what you're proposing has been refuted, and we have been warned to not do since over 1400 years ago

Hope this explains all

Feel free to ask any more questions

Best Regards

I know nothing of angels, but I know plenty about humans.  To insult a man is not ordinarily blasphemous; and man by his very nature is imperfect and capable of mistakes. 

It is reasonable to suppose that a man could recite the "message" (the Quran) without errors, and if he did make an error Allah could correct him.  What I said was that there is no logical reason to suppose that Muhammad was correct in everything he said or did; and your quotes from the Quran do not support such a claim.

I've already mentioned the degree of reverence, the protection from insult, infallibility, the function of defining doctrine, and authority that transcends time and space.  However, I think it's more important to know what Muslims would consider to be the attributes of a partner to Allah.  Aside from the error of addressing prayers directly to Allah, what else would constitute the sin of shirk?