At a recent Q&A time, the above question was raised and I attempted to give a nuanced answer that demonstrated human closeness but philosophical distance. Here is a three part answer.
- By virtue of being created, all humans can be considered God's offspring. In a sense then we can all be called children of God. Twentieth century theological liberalism took this motif and ran with it and referred to the brotherhood of humans and the fatherhood of God. In this fashion a Christian could technically, or by dictionary definition, refer to a Muslim as a brother or sister simply as a fellow human. This way of referring to Muslims has been done frequently by Roman Catholic popes in the 1980's and 1990's with the following as an example:Pope John Paul II spoke to a largely Christian audience in Bangladesh on November 19, 1986 and he used the term "Muslim brethren." From his speech: "You must try to show your Muslim brethren and the followers of other religious traditions that your Christian faith, far from weakening your sense of pride in your homeland and your love for her, helps you to prize and respect the culture and heritage of Bangladesh." It appears he has two categories of non-Christians, namely "brethren" who are Muslims and "followers of other religious traditions." (Source: "Vatican and Papal Statements on Islam") Earlier a study group commissioned by Rome in 1977 (called the Muslim-Christian Study Group - GRIC) issued a statement to the effect:..."in the same way Muslims and Christians should recognize each other first of all as believers, 'brothers in faith in God'. In this sense, and this sense alone, we acknowledge that the expression 'inter-religious ecumenism' applies to us."
- From a Muslim standpoint, the sense of solidarity within its exclusive community is conveyed by the word 'ummah'. That is, it is a body of Muslim believers who assert that only Muhammad can be the final prophet and that as the Indian Muslim author Iqbal stated, "love for Muhammad runs in their veins." Thus within the 'ummah' which is an exclusive group the term "Muslim brethren" can apply.
- From a Christian standpoint, believers who are not only created, but have been re-created, can refer to each other as brothers and sisters in Christ. They all have been adopted into the family of God the Father and can refer to God as 'Abba Father' as their 'older brother' the Lord Jesus does. As with the particular beliefs of the Muslim 'ummah' the Body of Christ is exclusive in that single allegiance to the Trinitarian God, namely the Father and the Son and Spirit is mandatory. Jesus is considered the final revelation.
Observation:
The phrase "Muslim brethren" as used above has a potential for creating category confusion. That is because it takes the wide generic category of fellow creatures and then applies a term that has traditionally been used within the Church for those who know God as Father through Jesus Christ the Son. It blurs the vital distinction between creation and re-creation and in effect Christianizes Muslims who do not want to be Christianized due to their allegiance to Muhammad as Allah's apostle.
A better way?
The Apostle Paul approached the people of Lystra and Athens [Acts 14/17] with a posture that they were fellow humans as himself. Yet he did not Christianize their religions, but rather told them to turn from "worthless things" to the Living God. To demonstrate this fellow humanity with Muslims, would it not be more worthwhile to combine both humanly closeness and the particular distance of belonging to a completely different body of believers? In an attempt to do so, some Christian believers in some Muslim majority countries refer to Muslims as their cousins. This seems much more useful than what seems to be the theologically careless use of the term "Muslim brothers and sisters."
What are your thoughts?