Answer
Walaykum Asalam wa Rahmat Allah dear Sister,
Thank you for sending your question.
We’re sorry to hear about your dad. May Allah grant him forgiveness and the highest reward in Paradise. Ameen.
With regards to your Mom, I would like to give you the following advice insha’Allah:
1- First and foremost, do your best to be kind to her, because we are ordered by Allah Almighty to be exceptionally good and excellent with our parents, even if they are non-believers.
Allah says in the Quran:
{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 and follow the way of those who turn back to Me [in repentance]. Then to Me will be your return, and I will inform you about what you used to do.} (Qur’an 31:14-15)
Abu Huraira reported that a person said:
‘Who amongst the people is most deserving of my good treatment?’ Allah’s messenger said, ‘your mother, again your mother, again your mother, then your father, then your nearest relatives according to the order (of nearness)’. (Sahih Muslim)
The more you act kindly towards her in general, the more this will soften her heart. And attribute your kindness to Allah Almighty’s instructions in the Qur’an and to the Prophet’s teachings.
2- Make dua to Allah Almighty that He opens her heart and eyes to the Truth. Continue to make dua for her in every prayer and whenever you can. Allah truly can change hearts and there are so many stories of parents who changed and were able to thoroughly find the Truth in Allah’s path.
3- If you don’t want to talk to her directly, you can send her whatsapp messages, an email, or Facebook messages that have sources that would teach her further. For example, Sheikh Yusuf Estes‘, Sheikh Ahmed Deedat’s, or Zakir Naik‘s videos are usually easy to understand and well-articulated.
There is also The Deen Show that has many resources on the subject of Christianity, and they are well presented. Find it here.
4- Try to privately speak with your little sister who is forced to go to church. Maybe show her the videos and resources and explain Islam clearly to her so she receives the message.
5- You may try to find someone your Mom trusts, like a respected Muslim Sister or an Imam, to speak to her instead and explain to her anything that isn’t clear to her and show her the meaning of Tawhid (monotheism).
This person can explain to her the falsehood of the trinity as well as the fact that the Bible has been edited and there are many versions of it—precluding it from being the direct word of God as opposed to the Qur’an.
And keep making dua, and insha’Allah, Allah will open many doors for you and help you. Don’t give up. Only do what you can, and the rest is upon Allah.
Please continue feeding your curiosity, and find more info in the following links:
https://aboutislam.net/reading-islam/research-studies/what-triggers-people-to-accept-islam/