There are two words in the Greek that we flatly and hastily roll into the one word, “life.” There’s bios, the word from which we derive “biography” and “biology.” When it is used in the New Testament (which is seldom), it is used to refer to the bone and flesh existence that we share with the animals. And then, there’s zoe (pronounced Zō-ā)—life which is full and complete and qualitative, the kind of life we see in Jesus, the life of God himself which he offers to share in/with/through us.
For the Christian, it should not come as a surprise that, when Jesus says, “I came that you might have life…”, he was not speaking of “bios.” (That’s a given—as we, like animals, eat and sleep and breath.) No, the word Jesus employs is “zoe”: “I came that you might have ‘zoe’ (the full and complete and qualitative life of God)… and have it abundantly.”
Someone once said: “Man’s greatest problem is not to add years to his life [that’s “bios,” quantitative existence], but life to his years.” (That’s zoe, quality existence!)
As still one other commentator put it: “If you have Christ, you have zoe; if you do not have Christ, you may have bios (biological, animal life) but you do not have zoe—real life, abundant life, fullness of life… the life of God… You are existing, but you are not really living.”
Perhaps C.S. Lewis best modifies and distinguishes between the two Greek words—helping us to see the incredible offer and claim of Christianity—when he writes that
Bios (biological) life is that life that comes to us from nature, the life that is always tending to run down and decay and needs to be nourished constantly with air, water and food. Spiritual life (Zoe), on the other hand, is the life which is in God from all eternity, which has always existed and will always exist… The difference between having bios and zoe is like the difference between a statue and a man. A man who changed from having bios to zoe would have gone through as big a change as a statue which changed from being a carved statue to being a real man… Now the whole affair which Christianity makes is this: that we can, if we let God have His way, come to share in the life of Christ… He came to this world and became a man in order to spread to other men the kind of life He has…”
The Christian life and the spiritual disciplines are very much about “zoe” and God’s desire to usher us into that existence. Transformation into the very likeness of Christ and His Zoe: the end of Christianity—including the devotional life [i.e., “tending the Means of Grace”]—is nothing less.