“You therefore, beloved, since you know this beforehand, beware lest you also fall from your own steadfastness, being led away with the error of the wicked…”
lest you also fall
The idea of “fall” implies that there was a point of stability in the past. The word “fall” is a term of apostasy. The book of Acts uses “fall” as a nautical term for a ship out of control or drifting off course (Acts 27:17,26,29,32). The Word of God cannot “fall away” from the purpose God gave it (Romans 9:6). Some fall from grace (Galatians 5:4).
“You have become estranged from Christ, you who attempt to be justified by law; you have fallen from grace” (Galatians 5:4).
“Beware, brethren, lest there be in any of you an evil heart of unbelief in departing from the living God…” (Hebrews 3:12).
A person who gets off course spiritually ends in spiritual weakness. “Unprincipled” (wicked) men will attempt to lead people away from confidence in the truth. They will attempt to make us abandon our relationship with God and His Word. This will blow us off course from God and will shipwreck our souls. We will run our spiritual ship aground.
Instability ends in a distortion of truth and spiritual ruin.
It is possible to fall from our soundness in Christ and lose our assurance of salvation. False teaching will water down our faith. We cannot lose our salvation, but we can lose the assurance of our salvation (2 Peter 1:10).
A stupid person is an unstable person. Stupid Christians are unstable Christians. Stupid Christians distort Scripture to their own ruin. All this starts with ignorance of the Word and then ultimately leads to spiritual ruin.
If we run into a difficult situation and do not know Scripture, we will distort the truth that we know. We will find ourselves in a jam. Instead of appropriating the principles of God’s Word to our experience, we will jump toward some panacea.
On the other hand, if we “grow in the grace and knowledge of our Lord and Savior Jesus Christ” (v.18), we will gain spiritual stability.