Allah says: “And if anyone of the Mushrikun (polytheists, idolaters, pagans, disbelievers in the Oneness of Allah) seeks your protection then grant him protection, so that he may hear the Word of Allah (the Qur’an), and then escort him to where he can be secure, that is because they are men who know not.” 9:6

Therefore, it is permissible for this disbeliever to join the congregation but he must be at the edge of the row and it is recommended that he is told to perform ablution in order for him to pray. though his prayer is invalid, but this may bring him closer to Islam when he practices some of it.

Sheikh, I have a question from a prisoner in America he wants to know, If a inmate non-believer ask to make prayer with the believers do we have the right to deny him? It’s not like we know what’s in his heart, whose to say after making salat with us that Allah will chose to make him a believer. Some people are saying that we should tell him that he needs to get into wudo and explain to him that we are praying to Allah and Allah only. Then you have others saying that he is in a state of disbelief so he can not enter the ranks until he takes his shahada. Please ask one of the Sheikh on this matter. To me it’s just like the man who killed 99 men and died before he became a believer. How can you say what’s in his heart, who are we except slaves of Allah.