How can rational proofs for the the existence of God be presented to a person who prays regularly but doubts His existence, especially after a personal experience that did not align with his understanding of the efficacy of adhkar in repelling jinn?

The answer to why jinn do not flee from adhkar (remembrances of Allah) lies in three matters:

1. The believer should blame himself, not his religion, just as it happened to Aban ibn Uthman when he forgot to say: "In the Name of Allah, with Whose Name nothing can cause harm..." and he was afflicted with paralysis, yet he did not doubt the hadith. Similarly, the treatment for waswas (whispers/obsessive thoughts) is by seeking refuge [with Allah] and spitting lightly to the left. 2. Supplication (dua) and incantations (ta’awwudhat) are like a weapon. If the weapon is complete, the striker is strong, and there are no impediments, then the effect will occur. However, if the supplication is not proper, or the supplicant is not present in heart, or if there is an impediment to the answer, then the effect will not occur. 3. The reason might be the presence of an impediment to the answer on the part of the supplicant, such as doubting the response, or supplicating as an experiment, or heedlessness of heart. Moreover, some jinn are Muslims and disobedient, and they may recite the Quran, so they are not affected by the recitation of others.