Why do some Christians bowdlerise words like "God", writing "G-d" instead? Some Christians bowdlerise words like "God", writing it as "G-d" or even "G d". This practice is likely inspired by the Jewish practice to do similar. But while some Jews explain their practice as a means to ensure that the names of God including the word "God" are never thrown out, I have never heard any Christians give such an explanation, which seems to me to be both more legalistic and more mystical than is found in most branches of Christianity. And it doesn't seem to square with how God inspired the authors of the Bible: considering that the New Testament's use of κύριος (lord) for the Tetragrammaton could be considered a bowdlerisation, if this practice was God's intention, it seems to me that he could easily have inspired the New Testmanent's authors to do likewise for θεός (god).

What reasons do these Christians give for this practice? Why is it sufficient to obscure one letter but still write the two consonants, shouldn't the whole word be avoided? (Do they also avoid writing words like "godly"?) And do they explain why, if it's either wrong or imprudent to write "God" in English, God did not inspire the Biblical authors to avoid the Hebrew and Greek words for "god"?
In Christianity there are hundreds of denominations and subgroups of Baptist, Pentacostal,    Methodist, Lutheran, Church of Christ, Church of God- Cleveland, vs Church of God Holiness, and countless splits over the centuries, so it's impossible to know all the subtle teachings.
I have been in ministry in 3 countries - USA and 2 in Europe and and lived in 11 states, and while I'm familiar with this practice, it's not the official teaching or practice of any Christian denomination that I know of.
I'm not disputing that some Christians do this, but the point is that it is usually some variation of Hebrew Roots movement, or Messianic Jewish groups, and like the practice of snake handling, it is a fringe practice and would be a fraction of 1%, and is not representative of mainstream Protestant Christianity.
To answer your question - let's assume there is a branch of Hebrew Roots Movement that uses this, or some other offshoot fundamentalist sect that teaches this. The origin of this practice comes from the Jewish concept that the name of God is so holy that you can't utter it - This was specifically for the special name of God YHWH, which is transliterated as Yahweh.
This was extended from not pronouncing this sacred name of God, to not writing it out fully.
This was not a strict command in the Torah that you can't write or say God's name, even for Jews, [5 books of the Law] nor is it in the Old Testament. It came about by Jewish tradition.
As you indicate, there are many other names for God in both the Old and New Testament, and these names indicate his special attributes and character- Elohim, Adonai, Lord, Christ, Alpha and Omega, the Great I AM, Kinsman Redeemer, Everlasting Father, Jesus, Emmanuel, El Shaddai, Yeshua Ha mashiach and many others.
If God didn't want us to say or write God's name, then Jesus would not have used God's name in the Model Prayer, when he taught the disciples how to pray, &quot;Our Father, who art in Heavean, hallowed/holy is your name.&quot;
Also, the fact that we have dozens of names all through the Bible, it's very inconsistent and legalistic to arbitrarily choose one to write with only consonants like G-d.