The author is obviously familiar with military special forces action - the main character was in the Army Rangers and Air Force just like the author.
Why is there evil in the world? What can save us from ourselves? These are two BIG questions posited in the telling of the tale. They are not posited quite so blatantly as I just did, nevertheless they are still there.
The partial answer to the first is perhaps it is a virus - a virus which does not necessarily attack and destroy our bodies, but one that infects us in other ways. These attacks are upon our morals and our consciences - allowing us to be cruel and evil to one another. The result is wars, murder, crime, torture, rape, pornography, torture and a myriad of other maladies. And just like lung cancer - not everyone who smokes gets cancer - not everyone is equally affected by this plague.
Someone has found a way to modify that virus, or it mutated so that those infected have a different attitude towards these evil activities. It also has the side benefit that it heals physical illness or wounds (sort of like Wolverine of the X-Men). Now, if this virus could be spread around the world, peace would reign - theoretically. We would return to the 'Garden of Eden', hence the name.
Of course there are bad guys, including agencies of the US government that do not want this virus spread.
Where did the original virus originate? Naturally, or space aliens? The story doesn't quite get around to blaming evil solely on the virus, but it also doesn't hold out much credence to the possibility that there is a God. On the other hand, the main character kind od believes in God and prayer - i.e., he prays, but he attributes his change in moral attitudes to the virus, not God.
The author does a pretty good job of wrapping up the story so the cliff hanger ending does not make you go, "Oh, crap" in the next to last chapter. The last chapter takes us into the rest of the series, and takes the story in a totally different direction. Hmmmmmmm. The action scenes are well described, but some of the dialogue suffers. That's why I couldn't give it a higher rating. I would give the second book a shot to see if the author can keep the story going.