Good question but i also have a question for you.
Q. Where does faith leave the little children? How are they saved or are they doomed because they don't understand?
You see, Christ came to save the world (whosoever) not to condemn it and He saves by love for He loved the world- not faith alonists.
Children and all those people who haven't been presented by the law (commandment to love)- basically, all who never hear of Christ (children/ disabled/ e.t.c) are saved by Christ because the law brings to the fore our sins, but in their case, there's no law so sin has no sting in them or rather is overcome by the works of God.
For the rest of us who have received the law and all the law is fulfilled in one commandment (love one another), sin is exposed and judgement abides unless we become one with the one who fulfilled the law. Becoming one with Him is knowing Him and knowing Him is loving one another the bible has said.
A muslim who has rejected Christ and His works of love and His command to love has no faith and therefore his works of love are futile.
John 14:15
If you love Me, you will keep My commandments.16And I will ask the Father, and He will give you another Advocate to be with you forever
John 14:21
Whoever has My commandments and keeps them is the one who loves Me. The one who loves Me will be loved by My Father, and I will love him and reveal Myself to him."
John 15:10
If you keep My commandments, you will remain in My love, just as I have kept My Father's commandments and remain in His love.
1 John 2:3
By this we can be sure that we have come to know Him: if we keep His commandments.
1 John 5:3
For this is the love of God, that we keep His commandments. And His commandments are not burdensome,
2 John 1:6
And this is love, that we walk according to His commandments. This is the very commandment you have heard from the beginning, that you must walk in love.
1 John 3:
14We know that we have passed from death to life, because we love our brothers. The one who does not love remains in death.
15Everyone who hates his brother is a murderer, and you know that eternal life does not reside in a murderer.
16By this we know what love is: Jesus laid down His life for us, and we ought to lay down our lives for our brothers.
17If anyone with earthly possessions sees his brother in need, but withholds his compassion from him, how can the love of God abide in him?
18Little children, let us love not in word and speech, but in action and truth.
19And by this we will know that we belong to the truth, and will assure our hearts in His presence:
20If our hearts condemn us, God is greater than our hearts, and He knows all things.