Does God forgive those who have committed major sins, such as fornication and reciting the Qur'an in the toilet while seeking help from Satan, and is his act considered polytheism?

Reading (recitation) that involves seeking the help of jinn is not permissible, as it is a form of enjoyment that is blameworthy in Islamic law, as stated in the verse: (And on the Day He will gather them all together, [He will say], "O company of jinn, you have [misled] many of mankind." And their allies among mankind will say, "Our Lord, some of us benefited from others, and we have attained our term, which You appointed for us." He will say, "The Fire is your residence, wherein you will abide eternally, except for what Allah wills. Indeed, your Lord is Wise and Knowing.") The benefit derived by humans from jinn is the fulfillment of their needs, and the benefit derived by jinn from humans is their obedience to them. Seeking refuge with the jinn only increases one's burden, as stated in the verse: (And indeed, there were men among mankind who sought refuge in men among the jinn, so they [the jinn] increased them in burden.) Whoever believes that jinn can harm or benefit independently of Allah is a polytheist (mushrik). And whoever believes that they are merely a means that may fulfill a need with Allah's permission, this is an act of disobedience. Allah forgives all sins through sincere repentance, for the one who repents from a sin is like one who has no sin.