5. ANSWER 3 (from West Africa)
Concerning this important question: I would like to answer it by sharing about a similar experience that happened in the church of a Pastor friend of mine a few years back. The similar situation caused a lot of confusion and division in his church among the congregation. There was a brother in his church, who was a Muslim convert, but a very faithful, diligent and devoted worshipper after his conversion five years earlier. He joined the church, together with his two legally married wives under the Islamic law. Because of his very active role in the activities of the church, and for ministering the Gospel to people at all times, which converted many souls from Islam and from other religions to Christ, the Pastor decided to promote him in the church to the rank of a deacon, and also to become one of the counselors in the church to be counseling members and people in the church. But to the Pastor's shock and surprise, 70% of the elders and leaders who are decision makers in the church objected fiercely to this decision, simply because of the brother's polygamous status. This was especially the case with the female part of the congregation, who felt that this could tempt or encourage their husbands too, to think of having second wives. These women and elders threatened to quit the church in masses if the Pastor insisted on carrying out that decision of making the convert a deacon and a counselor, some even threatened to have him removed as the Pastor of the church.
But on the other hand, there were around 30% of the members, mostly men, who were in favor of the Pastor's decision. They insisted that the Pastor should go on with his decision without fear, because of the brother's very active role, sincere devotion, strong faith and the many souls he has converted into the church, which was evident for all to see.
With this situation the Pastor was confused and didn't know what to do, because of the numbers of the majority who were opposed to this decision. Instantly the situation started affecting the progress and well being of the church. A lot of division, backbiting and hatred started arising in the church, and many meaningful members started deserting the church. When the Pastor tried all possible means to solve the problem and failed, he called me one very early morning seeking my assistance. He sounded very devastated and was in tears. He said that the way things were going he was afraid the church would collapse very soon, because he had lost very important members of the church in only two months, and that even his life was in danger. He begged me to please come and visit him as soon as I could. I accepted this offer immediately because of its urgency and importance, but I told him to be prayerful and put his trust in Jesus, because Satan can use this to break a church. The Pastor told me that he believed that my being a convert, and with the knowledge that I have acquired during my studies and counseling courses in the Bible School on how to manage critical church crises, he believed that I would be of great help and be able to rectify the issue.
I told the Pastor friend that I was not the one that was going to rectify issues or find a solution to the problem, but Jesus Christ is the only one who can do that and beyond human imagination. After arriving there and praying to Jesus for his guidance and direction, the Holy Spirit told me he would be in control. Christ directed me to first meet with the convert brother in question alone, and that I should share my testimony with him. Also that I should share with him Romans 14:1-15, which talks about the weak and the strong in faith, and the need for us as believers to forfeit our rights when the need arises, to prevent our fellow brother from stumbling in his faith, because of our acts or of what we eat or drink, even though it maybe our absolute right to do so. I implored the brother that for this reason, in order to avoid that the faith of the brethren, who are opposing him, would be destroyed, he should renounce and not accept the deacon and counseling positions, for peace to be restored in the church, because this was the only bone of contention, and before that the congregation had accepted him into its fold as one of their brethren. I shared and illustrated to him the persecution that many other converts in other countries are experiencing for worshiping and serving Jesus after their conversion. So for this reason, he should count himself lucky to find himself among a church that accepted him to worship with them without any risk or danger.
But nevertheless, I let him know that he is fully accepted by Jesus and he is a true Christian, and that whatever happened in his life before accepting Jesus as his personal Lord and Savior that doesn't have anything to do with his present status before Christ, as a Christian or as one of His faithful followers. So, even though human or fellow Christians may have a different view about him concerning his polygamous status from the time before his conversion, this has ABSOLUTELY NOTHING to do with God's and Jesus' view about him or his relationship or worship. Therefore his polygamous status is not a sin before God.
I also met later with the other parties and I used the same verses of the book of Romans to minister to them, as well as letting them know that the convert brother has committed no sin, because polygamy was accepted in his former religion as a divine permission before joining with the body of Christ. But nevertheless, the brother has denounced his intention to accept the positions of being a deacon and a counselor. So peace was restored in the church and all the members that left returned back to the church. And to the glory of God, few weeks later my Pastor friend called me to inform me that all members of the opposing party had finally agreed to his decision of making the convert brother a deacon and a counselor in the church - PTL.
I think this story will be of help in this present situation and in answering your question. But I want the convert in question to be ready and to know that this is one of the things any convert should expect and be ready to face at any point in time. It is part of the price to pay for our conversion/salvation.
But I will also like to add this fact on the side of any convert's multiple wives: if it happened that after the conversion of a Muslim brother, if one of the two wives is feeling or willing to quit the marriage from her own will or self decision, for reason of not wanting to quit Islam or for any other reasons, the brother shouldn't hesitate to let her go. But it is not right for him to leave or divorce any of his two legally married wives from the time before his conversion. God is not in support of that, though people may have diverse opinion about this. Some Pastors believe that only the first wife should be retained while the other wife/wives, should be sent away. But in my view this is a wrong perspective.