Well... To me it seems that one of the ways in which you can make a decision on your faith is to decide on your belief in Allah/God
There are many different cases to be made for either side; the case supporting the existence of God can generalised into arguments pertaining to religion in general.. Richard Dawkins (staunch Darwinist) makes a rather strong if somewhat controversial case explaining that intelligent life can evolve randomly without the need for a sentient being in 'The Blind Watchmaker'.
One could also say that the universe and its origins can be explained by science, or that it is inconceivable that God's design for the world should be so 'flawed' (referring to the William Paley's watchmaker argument).
Also, there are several Bible references of God ordering the killing of many people in the Old Testament (some speculate that this is merely a reflection of Jewish culture at the time, to be interpreted in the context of these enlightened modern times?) although I suppose Islam perceives other religions to be untrue, so I am not sure how useful that argument really is to you.
One could also think on the basis of the First Cause argument (that every event was caused by a preceding one) which is often attributed as supporting the existence of God because he is 'the First Cause' of the universe. Personally I find this argument fundamentally flawed, as it begs the question as to who caused God, thus it implies an eternal universe.
Some of the social issues such as women's rights in the Middle East also seem to be at odds with modern society, although can this be considered a sexist misinterpretation of the Qu'ran?
Alternatively, one could be drawn to the conclusion that the world's intrinsic beauty provokes such a feeling of the numinous that a supremely beautiful being such as God may be the only logical explanation.
Moreover, contrary to the hateful message that ISIS and other such groups have conveyed, one may be drawn to the love and compassion that is prevalent throughout the religion of Islam and indeed the world (in general). Desmond Tutu (a Christian, I know!) has rightly pointed out that love far outweighs hate. But, do we need religion in order to feel love and compassion?
Crumbs, it's 2:30, I'd better give it a rest. What I have splurged above is merely a slither of the arguments that can be made for either side (consider it a starter pack if you will 😉). Thank you so much for this opportunity to reanalyse my own faith and ideas about religion, it has been most intellectually stimulating!