According to the 109^th Surah of the Qur’an, Muhammad and the unbelievers did not worship the same Being:

Say: O disbelievers! I worship not that which ye worship; Nor worship ye that which I worship. And I shall not worship that which ye worship. Nor will ye worship that which I worship. Unto you your religion, and unto me my religion. S. 109:1-6 Pickthall

The problems that this Surah poses should be apparent to anyone familiar with both the Qur’an and the Islamic traditions.

First problem: Whom exactly is this Surah referring to?

(a) The People of the Book (Jews, Christians, perhaps Sabians)?
(b) The Meccan idolaters?

The Qur’an itself does not specify whom Muhammad is supposed to address this way.

Second problem: Whether it is option (a) or (b) above, Surah 109 contradicts other passages in the Qur’an which state that both groups were worshipping the same God as the Muslims.

Passages claiming that group (a) worshipped the same God:

Surely those who believe, and those who are Jews, and the Christians, and the Sabians, whoever believes in Allah and the Last day and does good, they shall have their reward from their Lord, and there is no fear for them, nor shall they grieve. S. 2:62 Shakir

Say (unto the People of the Scripture): Dispute ye with us concerning Allah when He is our Lord and your Lord? Ours are our works and yours your works. We look to Him alone. S. 2:139 Pickthall

Say: O People of the Scripture! Come to an agreement between us and you: that we shall worship none but Allah, and that we shall ascribe no partner unto Him, and that none of us shall take others for lords beside Allah. And if they turn away, then say: Bear witness that we are they who have surrendered (unto Him). S. 3:64

And argue not with the People of the Scripture unless it be in (a way) that is better, save with such of them as do wrong; and say: We believe in that which hath been revealed unto us and revealed unto you; our God and your God is One, and unto Him we surrender. S. 29:46 Pickthall

Passages showing that group (b) also worshipped the same God, even though they worshipped a host of other gods and goddesses along with Allah:

If indeed thou ask them who has created the heavens and the earth and subjected the sun and the moon (to his Law), they will certainly reply, "Allah". How are they then deluded away (from the truth)? Allah enlarges the sustenance (which He gives) to whichever of His servants He pleases; and He (similarly) grants by (strict) measure, (as He pleases): for Allah has full knowledge of all things. And if indeed thou ask them who it is that sends down rain from the sky, and gives life therewith to the earth after its death, they will certainly reply, "Allah!" Say, "Praise be to Allah!" But most of them understand not. S. 29:61-63

The worshippers of false gods say: "If Allah had so willed, we should not have worshipped aught but Him - neither we nor our fathers,- nor should we have prescribed prohibitions other than His." So did those who went before them. But what is the mission of messengers but to preach the Clear Message? S. 16:35

The pagans in the preceding passage were basically repeating what Allah supposedly said to Muhammad:

If it had been Allah's plan, they would not have taken false gods: but We made thee not one to watch over their doings, nor art thou set over them to dispose of their affairs. S. 6:107

Finally:

Surely pure religion is for Allah only. And those who choose protecting friends beside Him (say): We worship them only that they may bring us near unto Allah. Lo! Allah will judge between them concerning that wherein they differ. Lo! Allah guideth not him who is a liar, an ingrate. S. 39:3

In the above passage we see that the pagans’ MAIN direction of worship was Allah, that the other gods were only intermediaries/intercessors for the purpose of bringing them near to Allah! Thus, Allah was not just one of their many gods, but he was the main and highest one of all their gods.

In fact, the very name of the worst sin in Islam, SHIRK, means "association". Associating what (other gods) with WHOM? With Allah of course! The very name of this sin would not make sense if their gods were all distinct from Allah. It presupposes that Allah is one of their gods.

There is one other passage which refers to unnamed individuals who believed in Allah as the Creator of all things:

And if thou ask them, ‘Who has created the heavens and the earth?’ They will, surely, answer, ‘ALLAH.’ Say, ‘All praise belongs to ALLAH.’ But most of them have no knowledge. S. 31:25 Sher Ali

Whether this passage is addressing group A or group B, or even both, it is clear from this that the Quran presumes that the contemporaries of Muhammad knew and believed in Allah.

To summarize the above quoted passages:

1. Jews and Christians are said to worship Allah.
2. The pagans and idolaters also worshipped Allah, despite worshipping a host of other gods.

This being the case, how can Surah 109 claim that the unbelievers were NOT worshipping that which Muhammad worshipped? This is a clear contradiction.

To say that this is referring to the idols that the pagans were wrongly worshipping doesn’t solve the problem since:

1. How does a Muslim know that this is referring to the pagans? Where is this explicitly stated in the text?
2. Even if this were referring to the pagans, does not the Qur’an say that the pagans knew of and worshipped Allah, and therefore were worshippers of that which Muhammad worshipped?

It may be true that Muhammad didn’t worship (most of) their gods, but the fact remains that both Muhammad and the pagans worshipped Allah, and hence the pagans DID worship that which Muhammad was worshipping, in sharp contradiction to Surah 109:3.

For instance, the Quran has Muhammad saying that he doesn’t worship what the pagans worshipped except for Allah:

Say: O people! if you are in doubt as to my religion, then (know that) I do not serve those whom you serve besides Allah but I do serve Allah, Who will cause you to die, and I am commanded that I should be of the believers. S. 10:104 Shakir

Say (O Muhammad): I am forbidden to worship those unto whom ye cry beside Allah since there have come unto me clear proofs from my Lord, and I am commanded to surrender to the Lord of the Worlds. S. 40:66 Pickthall

These passages presuppose that the pagans were worshipping Allah, along with a host of other gods. Thus, Muhammad may have not worshipped all the host of gods of the pagans, but they were indeed worshipping Allah.

There are some translations which put 109:3 into the future instead of the present tense, turning it into a prophecy instead of a statement about the current situation. Yusuf Ali, for example, renders these verses as:

Say: O ye that reject Faith! I worship not that which ye worship, nor will ye worship that which I worship. And I will not worship that which ye have been wont to worship, nor will ye worship that which I worship.

This is no solution either. What would be the time frame that is referred to: next month, next year, or the rest of their lives? Surah 109 is generally held to be an early Meccan Surah, most inhabitants of Mecca were pagans at the time, and most commentators are convinced Muhammad is addressing the Meccan idolaters. The Meccan pagans, however, never abandoned their worship of Allah which would have been necessary to turn 109:3 into a true prophecy. On the contrary, as hostile as they originally were towards Islam, eventually Muhammad conquered Mecca and nearly all citizens converted to Islam with the consequence that Allah was then no longer just one of their gods but their one and only object of worship. Whether referring to the time before or after their conversion the Meccans always "worshipped that which Muhammad worshipped". Surah 109:3 remains in error whether interpreted as present tense or future tense.

Finally, some may claim that worship here refers to religious practices, i.e. that Muhammad didn’t engage in the religious practices of the pagans and vice-versa. This is wrong for at least two reasons. The text does not state that the disbelievers "do not worship HOW I worship", or "IN THE MANNER in which I worship", but that they "do not worship THAT WHICH I worship". It clearly is the object of worship not the method (i.e. the religious practices) that is referred to. However, even if we were to allow for this forced interpretation, it is still not correct, since the pagans were already observing four of the five Islamic pillars prior to Muhammad’s time. See for instance the article Muhammad and Idolatry.

Further discussion on the incoherence and the incompleteness of the Qur’an is found in these articles:

Sam Shamoun and Jochen Katz

Contradictions in the Qur'an
Answering Islam Home Page