Faith.
It puzzles me as to how some people can have such little faith, whether it be in God, their own religion whatever. Faith is learned, however i doubt it can taught. Soomeone can't just come up to you and start preaching, and in a matter of minutes you'll convert. Things are rarely so simple. However, I feel that faith is just like a ladder. In terms of Islam as in all religions that base, the ground is the most important. For without the basic knowledge, without the support of the ground how are you able to climb the ladder...
There are many steps, and though some may disagree with me on how I present this, the foundation of Islam is based on Usool-e-deen and Faro-e-deen, now I am sure you all know that. However once you have lived as a muslim, embraced Islam, and lived following Islamic rules, if you question the basics you will fall down the ladder. For example, if you start questioning whether Allah is just, or whether Prophet Mohammed had appointed Imam Ali, or the roles of the Imams, its like an earthquake has just occured, and you are now on a shaky ground, from that point on you can either grap on to the ladder, fall down, or fall into the hole created by the quake. The hole in the ground is a void, an empty world without religion, where you care more for yourself then your Lord. The only way to save yourself is to restablish your faith......
The point is whatever step of the ladder you are on, whatever level of faith you have, make sure that are fully supported and that no earthquakes occur....or even if they do, make sure you are stable and pray for closeness to God. Our lives, our actions are being judged, and it is He who will judge us only.

Remember,
"There is no compulsion in religion" 2:256
It is your choice whether to step on the ladder.