When Ali bin Abu Talib RA was asked about Faith in Religion, he replied that the structure of faith is supported by four pillars: endurance, conviction, justice and jihad.
Endurance is composed of four attributes: eagerness, fear, piety and anticipation (of death). so whoever is eager for Paradise will ignore temptations; whoever fears the fire of Hell will abstain from sins; whoever practices piety will easily bear the difficulties of life and whoever anticipates death will hasten towards good deeds.
Conviction has also four aspects to guard oneself against infatuations of sin; to search for explanation of truth through knowledge; to gain lessons from instructive things and to follow the precedent of the past people, because whoever wants to guard himself against vices and sins will have to search for the true causes of infatuation and the true ways of combating them out and to find those true ways one has to search them with the help of knowledge, whoever gets fully acquainted with various branches of knowledge will take lessons from life and whoever tries to take lessons from life is actually engaged in the study of the causes of rise and fall of previous civilizations .
Justice also has four aspects depth of understanding, profoundness of knowledge, fairness of judgment and dearness of mind; because whoever tries his best to under- stand a problem will have to study it, whoever has the practice of studying the subject he is to deal with, will develop a clear mind and will always come to correct decisions, whoever tries to achieve all this will have to develop ample patience and forbearance and whoever does this has done justice to the cause of religion and has led a life of good repute and fame.
Jihad is divided into four branches: to persuade people to be obedient to Allah; to prohibit them from sin and vice; to struggle (in the cause of Allah) sincerely and firmly on all occasions and to detest the vicious. Whoever persuades people to obey the orders of Allah provides strength to the believers; whoever dissuades them from vices and sins humiliates the unbelievers; whoever struggles on all occasions discharges all his obligations and whoever detests the vicious only for the sake of Allah, then Allah will take revenge on his enemies and will be pleased with Him on the Day of Judgment.
[Nahj ul Balagha]