There is a fair bit of debate about this issue. The actual name of this approach is called the insider movement. This methodology came about in an effort to help Muslims remain in their families and communities in order to be a gospel witness right where they live. Historically, Muslims who became Christians often left their communities and joined a church, many of which were planted by western missionaries. This meant that they often adopted western culture along with their new faith. This provided a solution to the problems of being a Christian in an Islamic setting, but any continuing witness to the community was lost.
The insider movement seeks to encourage Muslims to remain in their local setting, participate in their community and in the Mosque if possible. Although each individual situation is different, Christians with a Muslim background must decide how to proceed depending on the level of danger to themselves and family members. Many former Muslims are very open about their new faith while remaining in their local setting. Others have to be more secretive. The main point is that to be a follower of Jesus does not mean one has to adopt western means of worship or other western cultural forms that may come along with the gospel message. Christ is above culture and yet as the Incarnate One fits into every culture and language.
However, we also need to be cautious that we are not deceptive in this approach. We do not advocate pretending to be a Muslim in order to win converts to Christ. Nor do we promote the blending of Islamic and Christian beliefs (called syncretism). Rather we seek to convey the gospel message as clearly as possible, much like Paul when he says in 1 Corinthians 9:20-23, “To the Jews I became like a Jew, to win the Jews. To those under the law I became like one under the law (though I myself am not under the law), so as to win those under the law. To those not having the law I became like one not having the law (though I am not free from having God’s law but am under Christ’s law), so as to win those not having the law. To the weak I became weak, to win the weak. I have become all things to all men so that by all possible means I might save some. I do all this for the sake of the gospel, that I may share in its blessings.”
Most missionaries agree that it is important to contextualize the gospel so that it is understood in each culture. This is the nature of incarnation. The crucial question is one of identity. Can a Muslim hold on to their identity as a Muslim but be a follower of Jesus? (C5). Issues of identity are complex, but certainly the main identity of one who follows Jesus needs to center on the person and teachings of Jesus, his death on the cross and his resurrection. As believers from a Muslim background fall in love with Jesus, the Bible becomes more important than the Quran and Jesus becomes more important than Muhammad. As the Holy Spirit leads and guides these believers, they will discern with more clarity how they are to live out their faith in their own contexts, how they can disciple others, and how they can be discipled in following Jesus.