How can one differentiate between a believer and a hypocrite in order to apply the verse: "Humble towards the believers, powerful over the disbelievers," and what are the controls for being humble towards believers and firm towards disbelievers?

The fundamental principle for a Muslim is brotherhood and the faith-based love for anyone who utters the declaration of monotheism, unless that person openly commits sins, in which case they are to be disliked to the extent of their sin. We are not obligated to ascertain the condition of hypocrites. As for showing humility towards them, it is through modesty and mercy, not through arrogance and harshness. Allah Almighty says: "Muhammad is the Messenger of Allah; and those with him are firm against the disbelievers, merciful among themselves." So, firmness is towards disbelievers, and mercy is among Muslims. Gentleness and leniency are the norm in dealing with others, and one deviates from it only in specific situations, such as war and combat, where severity and strictness are required, as Allah Almighty says: "O you who have believed, fight those adjacent to you of the disbelievers and let them find in you harshness." As for non-combatants and those with whom treaties exist, the principle is righteousness and kindness towards them, a cheerful countenance, and gentle speech.