Question:
How can a Muslim know the extent of his Iman (faith/ belief)?
Answer:
This can be known through the extent of his fear and exaltation of Allah (Exalted be He), through hastening to do what Allah (Exalted be He) made obligatory and refraining from what He prohibited; these are signs of the strength of one’s Iman. A person’s tolerance in committing sins is a sign of weak Iman.
Strength of Iman is anything that constitutes fear of Allah, being mindful of Him, hastening to do what Allah (Exalted be He) made obligatory and being careful not to do what is prohibited. All the above attest to one’s strength of Iman and goodness. But, if a person is tolerant in committing sins, neglects Salah in congregation, is undutiful to his parents, slanders others and gossips, and consumes Riba (usury), these are all signs of weak Iman.
La hawla wala quwwata illa billah (there is neither might nor power except with Allah!).