it is a known fact that Jesus him self in his mother language of "Aramaic"which is a Semitic language like Hebrew and Arabic etc.he called God Alah and it was said the same way as Allah.even in Mel Gibson's clever movie
"the passion of Christ" you will here the actor in Aramaic saying bi-Alah which is the same as ya-Allah in Arabic or oh God in english.so when u curse the word Allah it is the same as cursing Alah and therefore you curse the name of God that Jesus(pbuh) used and Allah is the same word that Arabic speaking Christian use to refer to God also..