This is my simple law or equation. At times when my faith goes down say from 95% to 70% I would review in my head all the big coincidences of my faith. When I go through them I strengthen my faith: too much coincidences= no coincidence. With this equation you can attain faith as confirmed belief (too much coincidences) or faith by default (equal no coincidence or absence of strong evidence of disbelief). I will list down these coincidences:
1- Creation. 2- Intelligence behind creation. 3- A creator claiming his creation. 4- Purpose of creation. 4- Evil and good. 5- Enjoyment in both doing evil and good even in same person. 6- Conscience that is built by religion. 7- Inner desire to seek God. 8- Spiritual satisfaction by worshiping God. 9- Reaching out to God in difficult times. 10- Evil winning over good in earth. 10- Incomplete justice in our world and the reasonable belief in day of judgment. 10- Same messages of prophets and the way God inspired them (angels, visions and rarely too close like with prophet Moses). 12- Miracles of Quran (see topics in my blog) and Bible. 13- Why in hell prophets will suffer all they went through from their enemies and their followers unless they are very sure (faith) they carrying to us the truth. 14- We already believe in the unseen like electricity. 15- supernatural: visions, prophecies, witch crafts, connections with spirits and even Jinn or demons. 16- Even our social life has laws, for laugh the common law is "to say something unpredictable and in the same time funny but not silly", for laws of leaderships discovered by john Maxwell (21 laws) you break one of them and people will not follow you, and so on. 17- Human false pride that can deny the truth or rationalize the evil as well described in the Bible and the Quran.
So the spectrum of belief can be as sophisticated as examining the strict laws of cosmos and believe there is intelligence behind them or as simple as few visions in your life that came true or inner feeling that there is God. Thus God put in our heart and mind the ways to find him, everyone according to his sophistication. If you do not believe me review again the coincidences above. If you find them too much of coincidences it is not a coincidence (faith). If you still think they all are coincidences and there is no truth behind religion you are entitled to your disbelief. In Quran there is the freedom of faith. The only rare exception when people are aggressors to Muslims and too wicked that your own existence is only to have them Muslims. You know that they will start with a faith close to 0% but as they live between Muslims it will rise up and God will open their hearts to Islam. As I mentioned this is quite exceptional and self-defensive. You have to remember they tortured Muslims for 12 years and gathered all tribes to demolish them. Islam spread to most people through an open dialogue otherwise I would revert to be an Egyptian Coptic or a little pharaoh. To kill someone who reverted from Islam is extremism and with dialogue we can reclaim most of them. Extreme Islam and overzealous hate of Islam contributed equally to disfiguring this great religion. Even the west had decided who are the moderates (tyrants) and then blame Muslims for all of these resentments.