Come unto me, all ye that labour and are heavy laden, and I will give you work?

I’ve had the opportunity to dig a little further into scripture these days, and I’ve received some incredible insights regarding salvation. No…I’m not talking about Terminator, although it was an absolutely excellent display of action and cinematography (but let me not digress). In Christianity, it is professed that Jesus Christ came to this hopeless planet to restore, or save, mankind from certain death. For the sake of time, if you’re not familiar with the specificities of the story, please feel free to contact me, and I’d be glad to share.
Now, most Christians agree that Christ died, and through His death, gave us the ability to have eternal life. Why would someone want eternal life? As a believer in the Divine Creation, I believe that God created the first man and woman by hand. These two, very first, human beings were the epitome of what we, as humans, can be. Man and woman communicated directly with God as they lived their lives from day to day. As I’m sure you know, Adam and Eve ate the fruit, and the relationship between God and His supreme creations was severed. Fast forward a few thousand years later…Christ came to Earth, and died on the cross.

“For God did not send his Son into the world to condemn the world, but to save the world through him. Whoever believes in him is not condemned, but whoever does not believe stands condemned already because he has not believed in the name of God's one and only Son.” (John 3:17-18) There are a number of debates surrounding additional contingencies to the claim stated here. Is there some type of action which we must do in addition to JUST believing? That alone can't be enough? Is salvation THAT simple?