What is the ruling on doubt in Islam due to questions that raise the conviction that the religion is not true?

The greatest blessing is guidance to Islam and following the Prophet Muhammad, peace and blessings be upon him, for happiness and tranquility are only achieved by adhering to Allah's methodology. All other methodologies are misguidance and deviation, leading to misery in this world and torment in the Hereafter. Therefore, one must fear Allah, observe prayers, recite the Qur'an, and keep company with the righteous to repel the whispers of Satan.