Read this a long time ago here, so my recollection is a bit fragmented. MC is an archaeologist working with a crew on a dig. They unearth some kind of ancient artifact. Somehow (possibly by performing a ritual) he gets possessed by a related spirit or gains some power. A bit of that power also gets transferred to another crew member who is video-taping the ritual, and turns into the antagonist.
The MC develops a romantic relationship with a female crew member. The antagonist is obsessed with the same woman and later mind-controls another woman to resemble and act like her. There is also an ex-Mossad husband-wife pair who befriend and help the MC. All of them turn out to be re-incarnated (or modern versions of) ancient people connected with the artifact.
In the end the good guys win and evil is conquered and all that jazz, so yay for us all.
Hopefully this gives enough clues to the intrepid readers here in identifying the story. Thanks in advance, and the lucky winner to correctly identify the story gets a free one-way trip to that dig site.