Saved?

Heb 10:26-29
26 For if we go on sinning willfully after receiving the knowledge of the truth, there no longer remains a sacrifice for sins,27 but a certain terrifying expectation of judgment, and the fury of a fire which will consume the adversaries.28 Anyone who has set aside the Law of Moses dies without mercy on {the testimony of} two or three witnesses.29 How much severer punishment do you think he will deserve who has trampled under foot the Son of God, and has regarded as unclean the blood of the covenant by which he was sanctified, and has insulted the Spirit of grace?(NAS)

This passage is often used to say that we can lose our Salvation. The truth of the matter, however, is that we have been sealed in our Salvation.

Eph 1:13-14
13 In Him, you also, after listening to the message of truth, the gospel of your salvation-- having also believed, you were sealed in Him with the Holy Spirit of promise,14 who is given as a pledge of our inheritance, with a view to the redemption of {God's own} possession, to the praise of His glory.(NAS)

If God chose those who would believe in Him from the beginning, how can they fall? The Hebrews passage instead refers to those who appear to be saved, and perhaps think they are saved, but have not given their lives over to Jesus and accepted His gift fully. They are the "seeds that have fallen on the hard ground," the ones that have no root.

It is also important to note that this secure Salvation is a freedom in Christ and for Christ. It is NOT an excuse to continue sinning.

Rom 6:1-2
1 What shall we say then? Are we to continue in sin that grace might increase?2 May it never be! How shall we who died to sin still live in it?(NAS)