When faced with the horrors of Islamic terrorism it is mighty difficult to step back and ask whether there is mercy for Muslims. Can there be mercy for those who have no mercy?
When a horde of fanatical thugs burn churches, behead their enemies, rape nuns, murder priests and threaten mass murder it is not easy to be calm and observe that all Muslims aren’t like that and hope that peaceful Muslims will prevail and common sense and ordinary human compassion might, at last win through. Instead one begins to nod the head to those who growl, “We should turn the whole place into a parking lot…”
Nevertheless, we are commanded to love our enemies and do good to those who hate us, and the hopeless fact remains that revenge is endless and when violence is met with violence there is never a solution. The only way to overcome the Muslim threat would be an all out war in which one side won once and for all. Small hits of violence only escalate the conflict. From a human point of view how can one face such hate without returning hatred?
From a spiritual point of view is there mercy for Muslims? We know the Divine Mercy extends to all people, but how can one evangelize a people who will kill their own children if they decide to follow Christ? How can one evangelize those who would rather die a thousand deaths than convert to Christianity? How can one evangelize in a country that bans Christianity, persecutes Christians formally and declares war on Christianity? Can Muslims be saved without conversion? Can we hope that somehow they can find Christ within their Muslim religion? Is it possible for a Muslim to find mercy?
C.S.Lewis came up with an interesting answer to the problem. He begins with the basic belief that all who seek find and to all who knock the door will be opened. He then speculates that many within non-Christian religions do indeed, in their own way, seek what is beautiful, good and true. In his understanding all who seek beauty, truth and goodness with a sincere heart and total dedication will eventually find Christ the Lord who is the source of beauty, truth and goodness. It may not be until they cross death’s river that they see him and know him as the one they were always seeking, but he speculates that all will see him and those who always sought him will know him at once and love him, whereas those who claimed to follow him, but never did, will also see him and reject him as they always did.
Certainly a judgement of surprises is part of the gospel message. In the famous parable of the sheep and goats a good number who claimed to know and love the Lord, but never did his works of mercy are sent below while those who did not consciously know and love him, but did his works of mercy are welcomed into his presence. We may speculate, therefore that godly and compassionate Muslims might see Christ and know him while ungodly Christians might see him and reject him at the end.
This, of course, remains speculation. I have written on it further here for The Catholic Thing website. The article explores the question as Lewis presents it in The Great Divorce and The Last Battle.
All truth, beauty, and goodness is Catholic truth, beauty, and goodness. That is why we endorse and embrace all that is good, beautiful, and true not only within other expressions of Christianity, but also in other world religions.
So the Catechism of the Catholic Church states, “The Catholic Church recognizes in other religions that search, among shadows and images, for the God who is unknown yet near since he gives life and breath and all things and wants all men to be saved. Thus, the Church considers all goodness and truth found in these religions as a preparation for the Gospel and given by him who enlightens all men that they may at length have life.” 
Therefore we may hope that Muslims who truly seek all that is beautiful, good, and true may one day see Christ and know him as the goal of all their longing.
In the meantime, we are called to evangelize tirelessly so that those who dwell now in the shadows might come to know the glorious light of Christ.
Read the whole article here.