How can Guru Nanak be considered a Messenger of God when, according to Islam, Muhammad was the last and final Prophet?

Muslim scholar exposes truth by quoting Muslim sources that that Prophet Muhammad married Aisha at age 6 and consummated the marriage at age 9.

Muhammad ibn ‘Abdullĝh (born 570 in Mecca – died June 8, 632 in Medina), the founder of the religion of Islam, is regarded by Muslims as a messenger and prophet of God whom they consider to be the last (seal of the Prophets). Muslims consider him the restorer of the uncorrupted original monotheistic faith (Islam) of Adam, Noah, Abraham, Moses, Jesus among other prophets. During his life he was also active as a diplomat, merchant, philosopher, orator, legislator, reformer, military general and, according to Muslim belief, he was an agent of divine action.

Muhammad in Gurmat

Is Muhammad a prophet?

Muhammad was not the last Prophet sent by God.

ਮਹਾਦੀਨ ਕੇਤੇ ਪ੍ਰਿਥੀ ਮਾਂਝ ਹੂਏ ॥ ਸਮੈ ਆਪਨੀ ਆਪਨੀ ਅੰਤ ਮੂਏ ॥੨੭॥
ਜਿਤੇ ਅਉਲੀਆ ਅੰਬੀਆ ਹੋਇ ਬੀਤੇ ॥ ਤਿਤਿਓ ਕਾਲ ਜੀਤਾ ਨ ਤੇ ਕਾਲ ਜੀਤੇ ॥
Many Muhammads had been on the earth. They were born and then died in their own times (27). All the Prophets and saints of the past were conquered by Death, but none could conquer it.
(Guru Gobind Singh Ji, Bachitar Naatak – DG, p. 99)

Gurbani says:

ਹਰਿ ਜੁਗੁ ਜੁਗੁ ਭਗਤ ਉਪਾਇਆ ਪੈਜ ਰਖਦਾ ਆਇਆ ਰਾਮ ਰਾਜੇ ॥
In each and every age, He creates and sends his devotees and preserves their honor, Lord King.
(Ang 451)

Is Muhammad God?

Muhammad was not, but God still sent him and he ruled Arabia.
ਮਹਾਦੀਨ ਤਬ ਪ੍ਰਭ ਉਪਰਾਜਾ ॥ ਅਰਬ ਦੇਸ ਕੋ ਕੀਨੋ ਰਾਜਾ ॥੨੬॥
Then I created Muhammed, who was made the master of Arabia.26.
(Guru Gobind Singh, Bachitar Naatak – DG, p. 135)

Was Muhammad able to spread God’s message?
No doubt he spread God’s message, but he started his own ritualistic practices. He started his own religion in which he kept circumcised people. Circumcision is rejected according to Gurmat.
ਤਿਨ ਭੀ ਝਕ ਪੰਥ ਉਪਰਾਜਾ ॥ ਲਿੰਗ ਬਿਨਾ ਕੀਨੇ ਸਭ ਰਾਜਾ ॥
He started a religion and circumcised all the kings.
(Guru Gobind Singh, Bachitar Naatak – DG, p. 135)

He gave his own name. “La ilaha illa Allah” (There is no god other than God) is acceptable, however Muhammad asked his followers to also add on and recite “Muhammad rasool Allah” (Muhammad is the messenger of God). Guru Gobind Singh Ji says:
ਸਭ ਤੇ ਅਪਨਾ ਨਾਮੁ ਜਪਾਯੋ ॥ ਸਤਿ ਨਾਮੁ ਕਾਹੂੰ ਨ ਦ੍ਰਿੜਾਯੋ ॥੨੭॥
ਸਭ ਅਪਨੀ ਅਪਨੀ ਉਰਝਾਨਾ ॥ ਪਾਰਬ੍ਰਹਮ ਕਾਹੂ ਨ ਪਛਾਨਾ ॥
He caused all to utter his name and did not give True Name of the Lord with firmness to anyone.27. Everyone placed his own interest first and foremost and did not comprehend the Supreme God.
(Guru Gobind Singh, Bachitar Naatak – DG, p. 136)

In Bachitar Naatak, Guru Gobind Singh Ji writes about God discussing the history of his creation and creation of various Godly people who were sent to earth. But those people instead of reciting God’s name and showing people the Path of God, made their own path and people started praying to them. Muhammad’s name is in that list.

Was Guru Nanak a Messenger or Prophet of God?

Guru Nanak Dev Ji was not like Muhammad and the other human messengers of God. Guru Nanak Dev Ji was not a Prophet like the other world religious leaders. Guru Nanak Dev Ji is the living image of God on Earth. Guru Ji was the Light of God which came on Earth to shed light on the world. After so many religions failing to show people the Path to God, who else better than to show people the Way other than God Himself.

ਆਪਿ ਨਰਾਇਣੁ ਕਲਾ ਧਾਰਿ ਜਗ ਮਹਿ ਪਰਵਰਿਯਉ ||
ਨਿਰੰਕਾਰਿ ਆਕਾਰੁ ਜੋਤਿ ਜਗ ਮੰਡਲਿ ਕਰਿਯਉ ||
ਜਹ ਕਹ ਤਹ ਭਰਪੂਰੁ ਸਬਦੁ ਦੀਪਕਿ ਦੀਪਾਯਉ ||
ਜਿਹ ਸਿਖਹ ਸੰਗ੍ਰਹਿਓ ਤਤੁ ਹਰਿ ਚਰਣ ਮਿਲਾਯਉ ||
ਨਾਨਕ ਕੁਲਿ ਨਿੰਮਲੁ ਅਵਤਰਿ੍ਯਉ ਅੰਗਦ ਲਹਣੇ ਸੰਗਿ ਹੁਅ ||
ਗੁਰ ਅਮਰਦਾਸ ਤਾਰਣ ਤਰਣ ਜਨਮ ਜਨਮ ਪਾ ਸਰਣਿ ਤੁਅ ||੨||੧੬||
The Lord Himself wielded His Power and entered the world. The Formless Lord took form, and with His Light He illuminated the realms of the world. He is All-pervading everywhere; the Lamp of the Shabad, the Word, has been lit. Whoever gathers in the essence of the teachings shall be absorbed in the Feet of the Lord. Lehnaa, who became Guru Angad, and Guru Amar Daas, have been reincarnated into the pure house of Guru Nanak. Guru Amar Daas is our Saving Grace, who carries us across; in lifetime after lifetime, I seek the Sanctuary of Your Feet. ||2||16||
(Ang 1395)