How to respond to a believer engaging in immoral behaviour?

We sympathize with you in your difficult situation. Your daughter’s actions raise doubts over the sincerity of her confession. While we cannot provide personal counseling services, we can offer biblical instruction on these questions. 

First, your daughter’s poor choices do not necessarily invalidate her earlier confession. You may find the following article helpful: Can someone continue in sin and still be saved?

Even though her sin may lead you to doubt her faith, the Bible is clear that believers sometimes engage in severe sin even after calling upon the name of the Lord, and that God’s Word warns the believer to avoid such rebellion:

Heb. 6:4 For in the case of those who have once been enlightened and have tasted of the heavenly gift and have been made partakers of the Holy Spirit,
Heb. 6:5 and have tasted the good word of God and the powers of the age to come,
Heb. 6:6 and then have fallen away, it is impossible to renew them again to repentance, since they again crucify to themselves the Son of God and put Him to open shame.

Heb. 10:26 For if we go on sinning willfully after receiving the knowledge of the truth, there no longer remains a sacrifice for sins,
Heb. 10:27 but a terrifying expectation of judgment and the fury of a fire which will consume the adversaries.

These warnings are spoken to believers concerning the dangers of living in rebellion to the Lord Who has saved them. If your daughters’ confession was genuine, then she in living in open disobedience to the Lord Who saved her. She is daring the Lord to discipline her, and if she is a child of God by faith then you can be sure discipline will come in some form:

Heb. 12:5 and you have forgotten the exhortation which is addressed to you as sons,
“My son, do not regard lightly the discipline of the Lord,
Nor faint when you are reproved by Him;
Heb. 12:6 For those whom the Lord loves He disciplines,
And He scourges every son whom He receives.”
Heb. 12:7 It is for discipline that you endure; God deals with you as with sons; for what son is there whom his father does not discipline?
Heb. 12:8 But if you are without discipline, of which all have become partakers, then you are illegitimate children and not sons.
Heb. 12:9 Furthermore, we had earthly fathers to discipline us, and we respected them; shall we not much rather be subject to the Father of spirits, and live?
Heb. 12:10 For they disciplined us for a short time as seemed best to them, but He disciplines us for our good, so that we may share His holiness.
Heb. 12:11 All discipline for the moment seems not to be joyful, but sorrowful; yet to those who have been trained by it, afterwards it yields the peaceful fruit of righteousness.

The Lord disciplines His children to promote their righteousness, so if you believe your daughter is a believer, pray for the Lord to discipline her so she may repent of her sin and return to Him. 

Meanwhile, the Bible also teaches that Christians may not associate with someone claiming faith but living immorally:

1Cor. 5:9   I wrote you in my letter not to associate with immoral people;
1Cor. 5:10 I did not at all mean with the immoral people of this world, or with the covetous and swindlers, or with idolaters, for then you would have to go out of the world.
1Cor. 5:11 But actually, I wrote to you not to associate with any so-called brother if he is an immoral person, or covetous, or an idolater, or a reviler, or a drunkard, or a swindler — not even to eat with such a one.

Paul says we may not associate with immoral brothers and sisters, nor should we even eat with such a person. Paul calls these people “so-called” brothers and sisters, because their extreme sin suggests they may not truly be saved. Nevertheless, we are to take them at their word, so when they don't live according to that confession, we distance ourselves to avoid being caught in their sin. Paul’s instructions are more difficult to implement in cases of close family members, but nevertheless you should strive to live according to the spirit of Paul’s commands. Therefore, as long as your daughter claims to be a Christian, you should limit your association with her, explaining that God’s Word requires this in the hope she might be moved to repentance. If she repents, receive her back.

On the other hand, if you doubt her confession and believe her to be unsaved, then Paul says you may associate with her in the hope of witnessing Christ to her. Proclaim the gospel to her, reminding her of the penalty of sin, and asking her to repent and seek the salvation offered in Christ. 

You can also find many related articles listed to the side or at the bottom of this page.

Scripture quotations taken from the (NASB®) New American Standard Bible®, Copyright © 1995, 2020 by The Lockman Foundation. Used by permission. All rights reserved. www.lockman.org