If we consider Islam the true divine religion, do we honestly think that satanic forces, which are there to resist that divine religion and misguide the vast majority of people, would let it appear crystal clear to every individual? Won't lies be spoken and deceptions would be architected against that divine guidance to lure people in loosing their chance of salvation?
But Satan's wish is to lead them astray far away (from the right). (Chapter 4 An-Nisa:60)
Satan makes them promises, and creates in them false desires; but satan's promises are nothing but deception. (Chapter 4 An-Nisa:120)
He said: "Because thou hast thrown me out of the way, lo! I will lie in wait for them on thy straight way: "Then will I assault them from before them and behind them, from their right and their left: Nor wilt thou find, in most of them, gratitude (for thy mercies)." (Chapter 7 Al-Araf:16-17)
Were it not for the Grace and Mercy of Allah unto you, all but a few of you would have fallen into the clutches of Satan. (Chapter 4 An-Nisa:83)
We have to keep reminding ourselves that life is nothing but a test and realize that there will always be tricky situations in which one has to use his intellect, judge a situation without any bias and ask the help from only one God in order to succeed. If one is sincere in his effort, God won't ever let him go astray. That's the philosophy that Islam preaches i.e. of considering each individual to be a potential muslim unless and until they die on another faith or no faith other than Islam.
O ye who believe! Enter into Islam whole-heartedly; and follow not the footsteps of the evil one; for he is to you an avowed enemy. (Al-Baqra:208)
The Religion before Allah is Islam (submission to His Will): (Al-E-Imran:19)
