The phrase Jesus uses about passing from death to life by believing is interesting.  We still will die but we have moved from death to life?  With other things in John, there is a deeper meaning than the surface one.  Could be that we now have eternal life and that is what is meant.  Could also be that we move from a dead way of living to a way of living that is fully alive.  Eternal life starts now and because of what we have it changes everything about how we live now.  The future determines the present for Christians.  We often like to say that we are not guaranteed tomorrow and there is a sense in which this is true.  But in Christ, we are promised tomorrow, an eternity of them!