Will a good opinion of Allah remain a person's weapon, and will Allah reward him handsomely, and can he attain Paradise, if he commits a hidden act of shirk, whether out of ignorance or negligence, despite his good opinion of Allah and his shortcomings in his deeds?

Having a good (positive) opinion of Allah is incumbent upon the believer and must be coupled with fear that motivates action and self-rectification, following the example of the Prophets. Thus, whoever strives to rectify his deeds, being both fearful and hopeful, is on a path of great good. As for one who falls short in his deeds and claims to have a good opinion of Allah, he is not truthful, because having a good opinion of Allah necessitates striving in obedience. Indeed, "having a good opinion of Allah is good action itself." If a person who falls short in his deeds dies upon monotheism, he is among the people of Paradise, and Allah may punish him or forgive him. As for one who commits major shirk (polytheism) out of ignorance, he is excused, as is one who makes a mistake. However, whoever commits it knowingly and intentionally, and does not repent, will abide eternally in the Fire: "Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills."