Recently there has been a ban on the use of the word
Allah to refer to the Christian God.
What are the good alternatives to the word
Allah in countries where it is banned?
Tuhan is one of them.
The Christian God is given a wide range of names in both the Old Testament and the New Testament.
My first thought was to clarify with a generational phrase. You might say "The God of Abraham, Isaac, and Jacob," but that might confuse you with Jews. Also, Since "Allah" is the usual translation for "God" you would risk offending Muslims and breaking the law.
My second thought is "Yahweh." In the Old Testament God refers to himself as "I am." The transliteration of the Hebrew for this is "YHWH." The original vowels are unknown, but it has become common to pronounce it "Yaw - way" and spell it "Yahweh." A less popular pronunciation that has fallen out of vogue is "Jehovah."
You might also choose to say Jesus Christ, but I suspect that would even be more offensive to Muslims. It seems that believing Jesus is God is a major sticking point that upsets many Muslims.
Wikipedia has an interesting article on the names of God and gives a few other options that might work for you.
I am partial to "King of Kings" or "Lord of Lords." I'm sure there are those are common words, once translated into Arabic, that will not offend Muslims or break the law. From what I can tell "Tuhan" means "Lord," so using it in "Tuhan of Tuhans" would work (obviously I have Englishized the Arabic word).