What's Christian about the Christian faith?
The "obedience of faith" is shorthand for "the obedience of faith in Jesus Christ." It is the phrase "in Jesus Christ" that makes the Christian's faith distinctive and distinguishes it from all other faith.
The obedience of faith in Jesus Christ is not simply obedience to a moral standard. Others before us have been obedient to moral law (some more and some less) but for obvious reasons their obedience was not the "obedience of faith in Jesus Christ."
The "obedience of faith" for an Old Testament saint (see Hebrews 11, for examples) is the obedience that would rise out of his or her trust in God as he had revealed himself. It would be as genuine and as real as the Christian obedience of faith in Jesus Christ. But obedience of faith in Jesus Christ is distinctive; it is shaped by and expresses the developed purpose of God that has come to its completion only in Jesus Christ (compare Hebrews 11:39-40 as illustrative of what I mean). The OT obedience of faith could not have the content of the NT obedience of faith precisely because the Christ had not been revealed and the purpose of God had not come to completion in the person and work of Jesus Christ.
The obedience of faith in Jesus Christ is never less than but it is always more than an individual submitting him or herself to Christ. It's more than saying, "I trust you and will do what is right." The Christian's faith is Christ-shaped! It is more than doing good because Christ was good. The Christian's faith is acceptance of and commitment to Christ's person and agenda and method. It is the Christian's faith that constitutes him or her a Christian.
It's important to understand that the obedience of faith in the OT or the NT was not just about an individual's inner world. Biblical faith is never simply a personal response! Israel's faith—a faith common to all the individuals that made up the nation—wasn't just about their moral response by individuals that wanted to be "saved". The faith expressed in Israel's ordinances, liturgy, festivals, behaviour and so forth was a witness to the nature, character and deeds of God as he had revealed himself. Israel's united response of faith proclaimed things like God's faithfulness to Abrahamic promises and his deliverance from Egypt and the wilderness and his bringing them into the land he promised. If we had watched Israel's life for a while we would have learned about their history and destiny under Yahweh and not just that they were a nice honest mass of individuals who treated one another well. And we would have learned it because the national faith was designed to make it known! Their faith—as a nation and as individuals who were part of that nation—proclaimed an ongoing drama that God was unfolding and of which Israel was a part. In short, faith in the OT or NT was "gospeling" and not just the correct moral response to God.
But the NT "obedience of faith" bears witness to a part of the Story that wasn't yet available to Israel of pre-Christian times. The faith, ordinances and liturgy and lives of Christians as a corporate whole bear witness to the coming of God in and as Jesus Christ, of his life, death, burial, resurrection, exaltation and returning again and what those realities mean.
That is what's "Christian" about the Christian faith. To isolate our love for our families, our honesty in business or our patience under stress from the meaning of our faith and compare them with the same realities in non-Christians is a blunder. Our obedience that rises out of faith in Jesus Christ is so shaped and is to be immediately and inextricably connected with our role as the elect of God! Our lives of faith are designed to show that we have been called out of darkness into God's light to bear witness to Jesus Christ.
We are not simply "good living" people (though we ought to be pursuing a life of goodness). We are witnesses for God and what he has done! Isaiah 43:8-12 puts it in the plainest of terms. Israel has been evil in departing from God and he sent them into captivity; but now he brings them back home and the nations are called to see it all. Was Israel freed because the Medo-Persians liberated them or was it because God set them free? The nations are called to line up their witnesses to make their case and then God says to Israel "you are my witnesses." God had foretold all this and brought it to pass and Israel was the living proof of it. So it is with the Christian faith—it bears witness to God's ancient promises and their fulfilment in Jesus Christ.
It isn't all about you or me and about you and me "getting saved". It's bigger than that (though not less). It's about God and his eternal purpose and commitment toward the human family and how it is to be completed in Jesus Christ. That's what's Christian about the Christian faith.
2004 Jim McGuiggan. All materials are free to be copied and used as long as money is not being made.
Many thanks to brother Ed Healy, for allowing me to post from his website, the abiding word.com.