Does Hebrews 6:4-6 teach that a true believer can lose his salvation?

No. In that passage, the writer of Hebrews is speaking to the unsaved who have heard the truth and acknowledged it, but who have hesitated to embrace Christ. The Holy Spirit warns them, “You had better come to Christ now, for if you fall away it will be impossible for you to come again to the point of repentance.” They were at the best point for repentance–full knowledge. To fall back from that would be fatal.

Because they believe the warning is addressed to Christians, many interpreters hold that the passage teaches that salvation can be lost. If this interpretation were true, however, the passage would also teach that, once lost, salvation could never be regained. There would be no going back and forth, in and out of grace. But Christians are not being addressed, and it is the opportunity for receiving salvation, not salvation itself, that can be lost.

The believer need never fear he will lose his salvation. He cannot. The Bible is absolutely clear about that. Jesus said, “My sheep hear My voice, and I know them, and they follow Me; and I give eternal life to them, and they shall never perish; and no one shall snatch them out of My hand. My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of the Father’s hand” (John 10:27-29; see also Rom. 8:35-39; Phil. 1:6; and 1 Pet. 1:4-5). 

If you are in Christ, rejoice. Your salvation is secure forever. 

(Today’s post adapted from the MacArthur New Testament Commentary on Hebrews, p. 146.)