Is belittling sin and persisting in it—without deeming it permissible—considered disbelief?

Persisting in sins and treating them lightly, without deeming them permissible, does not expel a Muslim from the fold of Islam. Rather, such a person is a believer whose faith is deficient. The meaning of "The fornicator does not commit fornication while he is a believer" is that he does not commit these sins while his faith is complete. Those who commit major sins—other than Shirk (associating partners with Allah)—do not become disbelievers because of them. Whoever repents, their punishment is remitted. If one dies persisting in a major sin, then their fate is under the will of Allah: He may either forgive them and admit them to Paradise immediately, or He may punish them and then admit them to Paradise. It is incumbent to advise those who persist in sins with wisdom and good counsel so that they may repent to Allah.