… Simple question: What is the evidence for and against this claim, whether or not you consider it valid?..
Actually, Islam has more than “evidence” for this claim since the Qur’an does indeed offer the
proof.
"Then we inspired you (O Muhammad) to follow the religion of Abraham, monotheism; never was he an idol-worshiper." …
[16:123]
There is only One God who created one race of human beings, and communicated to them one message: submission to the will of God—known in Arabic as Islam. That message was conveyed to the first human beings on this earth, and reaffirmed by all of the prophets of God who came after them, down through the ages.
In the years after they were sent by God to their respective people, the Message that the Prophets taught gradually became lost and eventually the people went back to wrong and abhorrent practices such as idol-worship and associating partners with their Creator.
It is therefore no surprise then that at the time of Muhammad (pbuh), the pagan Arabs were worshiping idols in the Kaa’ba, despite them being the likely descendants of Abraham (pbuh) through his son, Ishmael (pbuh).
The essence of the message of Islam is that humankind should worship only One God by obeying His commandments, and should avoid worshiping God’s creation in any way, shape or form.
Jesus Christ (pbuh), born of the Virgin Mary, performed miracles and invited the Israelites to the same message of submission (Islam), as did all of the prophets who preceded him. He was not God, nor was he the ‘Son of God’, but was the Messiah, an illustrious prophet of God. Jesus did not invite people to worship himself; rather, he called them to worship God, and he himself worshiped God. He confirmed the laws of the Torah which Prophet Moses taught; he lived by them, and instructed his disciples to follow them to the finest detail. Before his departure, he informed his followers of the last prophet, Muhammad of Arabia (pbuh), who would come after him, and instructed them to observe his teachings.
In the generations after Jesus’ departure from this world, his teachings were distorted and he was elevated to the status of God. Six centuries later, with the coming of Prophet Muhammad (pbuh), the truth about Jesus Christ was finally retold and preserved eternally in the last book of divine revelation, the Qur’an. Furthermore, the laws of Moses, which Jesus followed, were revived in their pure and unadulterated form, and implemented in the divinely prescribed way of life known as Islam.
Consequently, the reality of the prophets, their uniform message, and the way of life which they followed, can only be found preserved in the religion of Islam, the only religion prescribed by God for man. Furthermore,
only Muslims today actually follow Jesus and his true teachings. Their way of life is much more in tune with the way of life of Jesus than any of the modern day “Christians”. Love and respect of Jesus Christ is an article of faith in Islam. Allah stressed the importance of belief in Jesus in numerous places in the Qur’an. For example, in Chapter an-Nisaa (4):159, He said:
} وَ إِنْ مِنْ أَهْلِ الْكِتَابِ إِلاَّ لَيُؤْمِنَنَّ بِهِ قَبْلَ مَوْتِهِ وَيَوْمَ الْقِيَامَةِ يَكُونُ عَلَيْهِمْ شَهِيدًا {
“And all of the people of the scripture must believe in him [Jesus] before his death, and on the Day of Resurrection, he will be a witness against them,”
) or something?