I Shall Loose None and Yet Some Will Be Cut Off
What follows is a slightly edited version of something I posted at Semper Reformanda, as further clarification of the post below this one.
It is clear that in Matthew 7 (which is a Gospel written primarily for the Jews) Christ is talking to God's Covenant people. Covenant people are God's people; these people were the wife of God, Covenantally speaking. These same people could, and many would, be cut off from the covenant people of God for rejecting Jesus Christ (see Rom. 11). Even today the Lord's covenant people (the Church) can be cut off as we see in Romans 11 and many other portions of the New Covenant Scriptures.
All God's covenant people, who are not predestined, before the foundation of the world, to persevere in the faith will hear these terrible words from the mouth of Christ: "I never knew you: depart from me..."
In one since all Covenant people are attached to Christ, this is by circumcision in the Old Covenant and by baptism in the New Covenant. And yet we see these same covenant peoples, in both Old and New Covenants, threatened with being cut off and we see that some are cut off from the People of God.
This is why "All" Israel was not Israel, and also why God's covenant people (branches connected to the vine -John 15:3-8) can be "cut off" and cast into the fire. Some of God's covenant people are wheat, whom God knows salvifically, and some of God's covenant people are tares. In the parable of the wheat and tare, some folks miss the fact that the parable is about the kingdom of heaven. The field is God's kingdom, and it contains both wheat and tares (Matt 13:24). It is to these people, the tares, that Christ will say "I never knew you: depart from me..."
We can be part of the people of God (saints/holy/set apart from the world), be part of the bride of Christ (the church), be in Christ (as branches, connected to a vine or olive branches connected to a tree) and at the same time be tares instead of wheat in the kingdom of God. In both Old and New Covenants we find that the people of GOd are a mixed multitude. All of them bare the outward sign of the covenant, circumcision in the Old and Baptism in the New, but not all of them have circumcised hearts and have made their calling and election sure (II Peter 1:10) by trusting in Christ as Lord and Saviour.
I think the big problem with the debate over whether or not one can loose his/her salvation has to do with the fact that we don't read these things in the biblical context of "Covenant." It is only in light of covenant that we can make perfect sense of the promises that none that the Father gives to Christ will be loss, and at the same time acknowledge the fact that some in Christ can be "cut off."
If we ignore covenant and play proof text table tennis, than we are implicitly saying that the Bible says contradictory things on this issue, and (as we all know) that is not the case.