Communicating differenty with different people

I found myself responding differently to different groups and cultures.  I realized that I speak my carefully and take more time to respond to cultural groups that different from me.  For example, I have a friend who is Middle Eastern and we began to speak about religion.  I almost came out and called God, Allah, to her but then I realized it would've been wrong.  She didn't tell me she was Muslim and I didn't want to assume because of her appearance (she wore the head dress most Muslim women wear).  So I kept saying high power but when my Christian friend joined the conversation I began to use the name God. 

I wish I had just said God from the beginning because it cause there to be an awkwardness between my Middle Eastern friend and I.  She noticed the difference and became less responsive with me.  If I could change it would just had use the word, God, from the beginning.