When is persistence in minor sins considered to make them major sins, and do minor sins turn into major sins simply by being committed twice?

Scholars differ concerning the definition of "insistence" (al-israr) that transforms a minor sin into a major one:

Some opine that the criterion is the frequent repetition of the act, indicating a disregard for religion, and this varies among individuals and situations.

Others believe that insistence relates to the resolve to repeat the minor sin and the absence of an intention to repent from it. Thus, whoever intends to repent is not considered insistent, even if the sin is repeated. And whoever resolves to repeat it is considered insistent, even if the act is infrequent.

Insistence means the heart's resolve to commit an act and not desist from it; it is procrastination and delaying repentance.

A Muslim is considered insistent if he does not promptly initiate sincere repentance from any sin he commits.

To overcome insistence, Al-Qurtubi advises reflecting on Allah's verses and His mention of Paradise and Hell, which generates fear and hope, and motivates repentance. He believes that this reflection is only possible through divine grace.

So, if a servant reflects, regrets his sins, and resolves to abandon them out of fear of Allah's punishment, then he is considered repentant. Otherwise, he is insistent upon disobedience.