Now this raises several questions. One is: Well, if our failure to hold fast our hope and confidence means we never were really partakers of Christ, what are we falling away from in verse 12?
Take care, brethren, lest there should be in any one of you an evil, unbelieving heart, in falling away [or turning away] from the living God.
In what sense can there be a falling away or a turning away from God if we never truly belonged to God?
One simple answer is that there can be real and painful falling away from a fiancée that is not a falling away from a wife. I think the way the writer wants us to think about this is given in the example of the people of Israel in verses 7–11 (= Psalm 95). He points out in verse 9 that the people “saw my works for forty years” and still they hardened their hearts against God (v. 8) and went astray in their hearts (v. 10). In other words they had seen God divide the Red Sea and show them great mercy to save them from Egypt. They had seen him give water from a rock, manna from the sky, guidance with pillars of cloud and fire, deliverance from enemies, good laws to live by, leniency for their rebelliousness. But in spite of all this they became hard in heart and stopped hoping in God. They wanted to go back to Egypt, they made idols and they murmured. This is what the writer means by “falling away from the living God.”
They had been swept up into the mighty workings of God. They had tasted his power and benefited from his Spirit and goodness. They had been enlightened with God’s revelation way beyond any people on the earth. And they had fallen away. So it was with some of the people in New Testament times. And so it is today. These people had been swept up in the signs and wonders mentioned in Hebrews 2:4. They had tasted the power of the age to come. They had been folded into a loving people and experienced measures of the Spirit’s work in their midst and in their lives. They had glimpsed the light of the gospel. They had been baptized and eaten communion and listened to preaching and probably had done some remarkable works themselves.
But, as with Israel, their hearts became hard, and an evil heart of unbelief got the upper hand, and they began to put their hope in other things rather than Christ, and over time they fell away from all the goodness that they had been surrounded with. And Hebrews says that the explanation of this is that they “had not become a partaker of Christ.” They had partaken of certain measures of enlightenment and power and joy; but (to use the words of Jesus) there was no root to the plant and it withered, while others were choked with worries and riches and pleasures of this life (Luke 8:13–14).
In other words, you can fall away from God to the degree that you have come close to the work of God—the love of his people, the light of his Word, the privilege of prayer, the moral force of his example, the gifts and miracles of his Spirit, the blessings of his providence and the daily revelation of sun and rain. It is possible to taste of these things, be deeply affected by them, and to be lost in unbelief, because Jesus Christ himself is not your heart’s delight and hope and confidence and reward.
Jesus taught these things over and over to warn against false assurance. For example, he said in Matthew 7:21–23,
Not every one who says to me, “Lord, Lord,” shall enter the kingdom of heaven, but he who does the will of my Father who is in heaven. On that day many will say to me, “Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?” And then will I declare to them, “I never knew you; depart from me, you evildoers.”
Prophesying, casting out demons, and doing mighty works in the name of Jesus do not prove that Jesus has “known” us, or that we are partakers of Christ. It is possible to do those things with a hard, unchanged heart. The evidence of “being known” by Jesus is that Jesus is our hope, our confidence, our treasure, our reward (Hebrews 10:24; 11:25–26). That is the inner reality that transforms our lives.
That’s one question: How can you fall away from or turn away from God, if you never were a partaker of Christ? And the answer is: there are many ways to partake of the nearness of God without trusting him and hoping in him and loving him. And so there are many ways to turn from Christ without having ever been a partaker of Christ himself.