I refer to the letter Others using 'Allah' will confuse Muslims . The word 'Allah' is pre-Islamic and has been in use by Christians before the advent of the Prophet Muhammad. Also, it may be of interest to the general public to know that since the first translations of the Bible were done in Malay in the 1600s, the word 'Allah' has been used.
The usage of the word 'Allah' has got to do with two words in the Bible. The word 'Lord' is rendered in Malay as 'Tuhan' while the word 'God' is rendered in Malay as 'Allah'. The Malay- speaking Christian community has been worshiping God with these words for 400 years now. This has been the tradition handed down.
Are we expected to stop because some might be confused? The Indonesian Bible uses the word 'Allah' not 'Alah'. Perhaps the writer is a little confused with the way the word is pronounced by Indonesian Christians. There are online resources to verify the spelling used in the Indonesian Bible.