Why do people write G-d in their posts, what, is 'God' offensive or something?

I suppose that some people would take the title, "god", to be a name of a 'foreign' god.

Exodus 23:13
"Be careful to do everything I have said to you. Do not invoke the names of other gods; do not let them be heard on your lips.
(2011 NIV)

Hosea 2:17
I will remove the names of the Baals from her lips; no longer will their names be invoked.
(2011 NIV)

Psalm 16:4
The sorrows of those who run after another god shall multiply; their drink offerings of blood I will not pour out or take their names on my lips.
(ESV)

a reply to: grainofsand

From what I can gather (as a Christian), it's a belief that writing "God" is somehow using the name "in vain", which isn't the case at all. Using His name in vain would be using it as an exclamation, for example, or as a curse, perhaps. We aren't told we can't use His name at all; only not to use it "in vain". Some are overly cautious about this, and leave out a letter as a result. I guess, for them, it's a way to avoid a sin they think they would otherwise commit, so I won't tell them to do otherwise. I don't personally see that as something we need to do, however.