What's your intention of adding name?

Also, it's called English name not Christian name. Not all Christians have an English name and not all people with English names are Christians. In workplace, people use English names as it's easier to remember.

As a Christian myself without an English name in my IC, I think it's silly to go all the way just to add it in. It might cause many problems in future. My baptismal name is not in my IC. I didn't even add my confirmation name when I was confirmed.

People usually change/add if there's an error. True story (as I can't reveal my real surname, I'll substitute letters): My grandpa's surname is XX but my dad's surname was XXY because the nurse made a mistake, adding an additional letter. However, it's the same pronunciation.

To avoid legal disputes regarding his will (people may argue that my dad is not his son because of different surname), my grandpa added XXY to his name. So, it's XX @ XXY ___ ____

If you're adding the English name just because of social pressure, I suggest not because the problems will outweigh the benefits.