People often confuse the doctrine of eternal security with the doctrine of the perseverance of the saints. But the two are entirely different things and operate according to different principles.

Free Grace people believe in eternal security, popularly called Once Saved, Always Saved (or OSAS for short), while Calvinists believe in the perseverance of the saints (or POTS for short).

Eternal security means that once you’ve believed in Jesus for salvation, you’re secure forever, no matter what you do or think afterward. That’s an entirely different claim than the Calvinist one, which says whomever God has predestined to be eternal saved will irresistibly come to believe in Jesus and continue in faith and good works until death because God is causing them to perseverere.

Unlike Calvinism, Free Grace theology believes in two truths: 1) eternal security and 2) the possibility of apostasy.

My friend Antonio da Rosa compiled a list of verses that show Christians can apostatize (slightly edited by me):

• A Christian’s faith can be “shipwrecked” (1 Tim 1:18-20)

• They can “depart from the truth” (2 Tim 2:17-19)

• Some have “departed from the faith” (1 Tim 6:20-21)

• They can “stray from the truth” (James 5:19)

• God’s “righteous one” can “draw back” (Heb 10:38-39)

• You can fall from grace (Gal 5:4)

• “In later times some will depart from the faith” (1 Tim 4:1-3) [Note: You cannot fall away from something that you were not once in]

• You can “deny the faith” and be “worse than an unbeliever” (1 Tim 5:8) [Note: You can’t be an unbeliever and worse than one at the same time.]

• Christian widows can “turn away to follow Satan” (1 Tim 5:14-15)

• People like Demas, Phygelus, Hermogenes, and other unnamed people could desert Paul for worldly ambitions (2 Tim 1:15, 4:10, 16).

• Christians can be “snared by the devil” and “taken captive…to do his will” (2 Tim 2:24-26)

If POTS were true, Paul wouldn’t have to warn believers against losing faith, because that would be impossible. The fact that Paul does have to warn Christians repeatedly against apostasy should convince you that Calvinism’s “perseverance of the saints” isn’t Biblical.

But if Calvinism is wrong, does that mean Arminianism is correct, and you can lose your salvation?

No. As Antonio wrote:

Yet God be praised. One thing is eternally off the table as a consequence: hell. (But many other consequences are available to God’s employ!)

Once you believe in Jesus—and it only takes a moment of faith—you’re born again and guaranteed never to perish, come under judgment, be condemned, or die. You have everlasting life. You will never be judged, perish, be cast out, or snatched away from the Father's hands (cf. John 3:16; 5:24; 10:28-29)

However, that doesn’t mean you can sin consequence-free. As Antonio hints, “hell” is not on the table, but there are “other consequences” that come with falling away from the faith. Free Grace writers, including our own Lucas Kitchen, have explored the positive things at stake (see here). I’m working on a little book explaining all the things eternally secure believers can lose. Suffice it to say that sin makes you miserable and isn’t God’s best for you. But He’ll be faithful to you, even if you’re faithless to Him, and nothing can separate you from God’s love in Christ Jesus (2 Tim 2:13; Rom 8:35-39).

So, to answer the original question, Can a Christian fall away from the faith? Yes, they can. They can stop believing, and they can stop obeying, but no matter what they do, they can never lose eternal life.