Greetings from China!
Thanks for welcoming me and the questions!
I am more than happy to share my thoughts regarding the worldview before I knew Lord Jesus Christ. As a Chinese, I was immersed in the culture of “kind of believing there is some God”. The concept of god has been there through literature works such as Journey To The West. Even though, the education here advocates atheism, most Chinese people (consciously or unconsciously) believe there is a god or maybe gods. We even have a saying “The gods are watching” (you can show Shuxia this Chinese version of the saying and ask her opinion about it: 举头三尺有神明). Most people want to be good and tend to believe there will be a return for both good and bad deeds. Chinese people are open to different belief as long as they don’t feel pushed by some aggressive believers.
I am sorry because I actually don’t have any helpful suggestion for you. I think the love you are showing her is very essential. In China, the mother-in-law and daughter-in-low relationship is very hard to deal with, I guess your love and care to for is already saying something. Maybe start talking about Chinese culture with her and try to get an idea about how she sees the world, sin, and justice? I have noticed that even I am in China with Chinese people around me in my life, our perception and understanding about life is so different that sometimes I feel I am one of the odd balls.
At last, I pray God gives you more wisdom to share the Gospel and opens the heart of your son and Shuxia because it is His work that people are saved!
Let me know if there is anything I can help : )