Edit: This first bit was after my not grokking the question. I'm leaving it anyway. Proper answer follows
Christen does not mean "to make Christian", it means "to anoint with oil", which is part of the Christian naming rite. (Christ is from the same root, meaning "anointed one").
Sain is sometimes used of people being named in religious rites without it being specific to any particular religion, and is popular as such in some Neopagan circles (pardon the pun), though ironically this in origin was specifically Christian, since it refers to the sign of the cross being made and is cognate with sign.
Clerk originally meant a member of the clergy (where we would now use cleric that was deliberately introduced to avoid confusion). It comes from a time when being literate and being clergy was essentially one and the same within Christendom, and indeed being literate remained the legal definition of clergy (saving you from execution for some crimes) well after this was no longer the case.
(Incidentally, while the Old English for both god and good was spelt god, these were two heteronyms, pronounced differently and coming from different roots. It wouldn't even have made much sense to say "God is good" at the time, as it didn't have the absolute sense it has now — if you'd said "God is good" people would have wondered what you were saying He was good for.)
Now for the actual answer to the question intended:
Some adjectives from the names of gods, that no longer refer solely to the gods in question:
Jovial, martial, saturnine, mercurial, erotic, anterotic (whether this is formed as not-erotic or from Anteros is unclear), chaotic.
The prefix geo- is from Gaia, and chrono- from Chronos.
Edit: Some more:
Hermaphrodite, dionysian, cereal, hygiene, echo, venereal, museum, herculean, volcano, nemesis, morphine & helium.
If we allow heroes, monsters, etc. as well as gods:
Oedipal, sisyphean, narcissist, siren, mentor and finally titanic if we allow a group of gods, as well individuals.
Some uses of Christian figures as expletives have become detached from their origin, so while someone who says "god-damn" would know where it came from, someone might say bloody or zounds not knowing they come from "by Our Lady" and "God's wounds" respectively. ("Our Lady" is a title used as a name, so whether you choose to count that or not, I don't know).