Assalamu alaykum. This question might be from Waswaas (devilish whisperings), but I will try to keep it simple as I suffer from Waswaas and need an urgent answer. It is well known that if you do Tahaakum to the Taaghoot (false gods), it is Kufr Akbar (major disbelief). Tahaakum means when two or more disputing parties refer their dispute to a third party in order to resolve it. So let us say that I am in my bedroom and am having an argument with my brother and tell him to leave my room. But he refuses to do so, so I tell my mom (who is a non-Muslim) to tell him to leave my room. Is this not a case of Tahaakum to the Taaghoot? I do not even know if I have commited Kufr (disbelief), and it is extremely distressing as I do not want to think about the fact that I could lose my Hereafter and spend eternity in hell. Please note that I do not have any intention nor wish to leave Islam and do not regard a person who does not judge according to the Sharia as legitimate in our Religion. How about if my youngest brother would like me to give him something from my money but I refuse, so he goes and tells his dad (who is a non-Muslim), and I knew that he would tell our dad but I still did not want to give him my money. Am I a Kafir (disbeliever) for not allowing him to go and tell my dad? How about if I follow the judgement that my dad passes, would that be Kufr even though I hate the judgement that he passed (if it was not in accordance with the Sharia)? Please answer very quickly. May Allaah reward you. Also, one small question that is extremely urgent, please: if an innovator (regardless of whether his innovation takes him out of Islam or not) runs Fiqh (jurisprudence) classes online but he teaches how to make ablution, how to pray, and the etiquette of invocations, and so on, would it be haram if I signed up for his Fiqh classes knowing that he will not mention his innovation in his Fiqh classes? (it is in an entirely different area than ablution and prayer, so he will not talk about his innovation there). Also, if he recited the Quran in a certain way and I imitate his voice and recitation of the Quran, would that be haram? May Allaah reward you.

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger. 

Seeking the help of your non-Muslim mother to settle the dispute between you and your brother or obeying your father in what is deemed lawful does not fall under the category of Tahaakum to the Taaghoot (going for judgment in one's disputes to other than Allaah). Islam legislated obedience to the non-Muslim parents in lawful matters and banned obeying them in whatever is unlawful. Allaah, The Exalted, says (what means): {And We have enjoined upon man (care) for his parents. His mother carried him, (increasing her) in weakness upon weakness, and his weaning is in two years. Be grateful to Me and to your parents; to Me is the (final) destination. But if they endeavor to make you associate with Me that of which you have no knowledge, do not obey them but accompany them in (this) world with appropriate kindness...} [Quran 31:14-15]

It is permissible to learn Fiqh at the hands of this person as long as he does not preach his religious innovation if he is truly knowledgeable of Fiqh and does not contradict the teachings of the Quran and Sunnah. Scholars have underlined that the Prophet, sallallaahu ʻalayhi wa sallam, permitted learning what is useful at the hands of non-Muslims; so it is permitted to learn (what is useful) at the hands of Muslims with greater reason. Some of the prisoners of war who were seized in the Battle of Badr were asked to teach the Muslims' children how to read and write as ransom, as was stated by Ibn Hajar in Fat-h Al-Baari and by Ibn Al-Qayyim in Zaad Al-Maʻaad.

Ibn ʻAbbaas said, “Some of the prisoners of war captured in the Battle of Badr could not afford to pay the ransom; so the Messenger of Allaah, sallallaahu ʻalayhi wa sallam, asked them to teach the children of Al-Ansaar how to write as ransom.” [Al-Bayhaqi in As-Sunan and Ibn Saʻd in At-Tabaqaat]

For more benefit, please refer to fatwa 89655.

Allaah knows best.