Nephilim by L. A. Marzulli

From the publisher (source: The Internet Book List):
Two years ago, Art Mac Mackenzie was a respected newspaper journalist with a wonderful family and a great future. Now he lives by himself, eking out an existence as a freelance writer. His faith in God, humanity, and virtually everything else is gone. Whats left is a pile of bills and the ache of his eldest sons death. Enter a woman in a psychiatric ward, with an off-the-wall story of how aliens abducted her, created a baby within her, and later stole it. From her seemingly twisted account springs the potential media story of the century . . . and more trouble than Mac has ever imagined. In this engrossing page-turner, Mac follows his story to Israel, where he comes across the remains of one of the nephilim: an ancient biblical giant, sired by demons and born of human women. Macs encounter is just the tip of a terrifying supernatural iceberg for the nephilim are back on earth. And Mac has stumbled onto their secret. Nephilim winds from the Holy Land to the Nevada desert, through mind-numbing dangers and choices that will affect the future of the human race. Just one hope stands between Mac and destruction: the power of the risen Messiah. But can it save Mac and his children from the evil spiritual forces that spawned the nephilim? Or fulfill his agonizing quest for meaning and purpose in life?

This book is part of the "The Nephilim Trilogy" series.
Here are some other books from this series: