Is a person considered a transgressor or one who violates the sanctities of Allah if he is afflicted with repeated masturbation due to intense thoughts about intimate relations with his fiancée, despite his perseverance in acts of obedience and his attempts to repent and lower his gaze, and sometimes resorting to watching cartoon sexual images, thinking that they are less sinful?

Allah grants repentance to His servant and bestows upon him chastity. The problem is not in the sin itself, but in despairing of repentance or having a weak will to repent. The servant must initiate repentance and not despair of Allah's mercy, for "the one who repents from a sin is like one who has no sin."

The hadith about violating Allah's sanctities does not apply to one whose soul slipped, but rather to one who belittles Allah's sanctities. It is not permissible to view lust-provoking images. It is obligatory to take measures for safety and to keep away from sin. Remember that persistence in minor sins is considered wickedness.