How can we strengthen faith in Allah, the Almighty, in our hearts?

Answer

In the name of Allah, through piety and self-accountability at least once a day. Imam Musa al-Kadhim (peace be upon him) said: “He is not one of us who does not hold himself accountable every day; if he does good, he asks Allah for increase, and if he does evil, he seeks forgiveness from Allah and repents.” Self-accountability is the first step on the path of self-reformation. Allah is the Guide.