John 3:36

"Whoever believes in the Son has eternal life..."   

A life with God is possible in the present even though that final life with God in all its fullness has not yet arrived. There is a tension in John's Gospel, and indeed throughout the New Testament, between "the already and the not yet." The new life has already begun in us with the coming of Jesus. The fulfillment of the kingdom, of eternal life, will not be different in substance from our life in Christ now. It will be complete. New life begins when we actively put our trust in the God whom Jesus shows us. The opposite of believing is disobeying. True faith is lived out in true action.