What is the ruling regarding the words uttered by a parent towards Allah Almighty when their illness intensifies, which include describing Allah with attributes that are not befitting Him, and are we considered partners in sin due to our inability to prevent them?

The aforementioned speech may lead its speaker out of the fold of Islam. Therefore, you must continue to advise, guide, and instruct him, and clarify that this world is a realm of trials, and that discontent with God's decree harms its speaker and changes nothing of reality. Indeed, the afflicted person, if he perseveres and seeks reward, will be recompensed his reward without measure. "Great reward comes with great affliction. And verily, when Allah loves a people, He afflicts them. So whoever is content, for him is contentment, and whoever is discontent, for him is discontent." And "On the Day of Resurrection, the people of ease will wish, when the people of affliction are given their reward, that their skins had been cut to pieces in this world with scissors." As for the issue of sharing in sin, if you deny this speech, clarify its error, and advise him, then you have fulfilled your duty.