We are commanded to honor our father and our mother but how can you honor an abusive parent who is not saved? Are we still commanded to honor parents, no matter what?
Honor you Father and your Mother
Exodus 20:12 “Honor your father and your mother, that your days may be long in the land that the Lord your God is giving you.”
The first four Commandments are given to mankind to show them how they are to relate to the Creator God but the next six are given to mankind for how we should relate to one another. Which is the first given to mankind relating to mankind? It is the Commandment to honor our father and our mother. On this Commandment, all the following five depend. Why do I say that? Because families are the glue that holds society together and if children are not taught to honor their parents, the following Commandments will all likely be broken. A child that honors their father and their mother will be less likely to not steal, to commit adultery when they become adults, to lie (bear false witness), to murder, or to covet. That is the reason I believe that God put the first Commandment given to human beings relating to human beings to be honor their parents because a godly upbringing increases the likelihood, though certainly not guaranteeing, that children will be obedient  in the society in which they will live.
The Abusive Parent(s)
The most difficult thing of all in honoring parents is to honor those who were abusive. How is this even possible? It isn’t without the power of the Holy Spirit. Living the Christian life is not hard…it is impossible without the power of God’s Spirit living in us, working in us, and enabling us to do anything good at all. So for unbelievers, this seems completely impossible but for Christians, we are commanded to honor our parents. God never said to honor our parents “unless they were abusive” or “only if they are believers.” What about when they are both unbelievers and were abusive? For one thing, you can’t blame someone for being an unbeliever. It’s like going up to a blind man and scolding him for not seeing where he’s going. Also, an abusive parent who isn’t saved doesn’t have access to the Holy Spirit so they have no ability to live a godly life. This doesn’t excuse their abuse, but it makes it more likely to occur in this fallen world. Perhaps their parents were like this. If they were beaten as a child, the likelihood of their being an abuser greatly increases. This doesn’t give them permission of course but it does make it more understandable. I am not saying that this gives them an excuse for abusing their children but these types of patterns can run through certain families for generations and continue on until someone breaks that vicious cycle. Perhaps you are that person or you have been the one that has broken that chain of dysfunction in your own family and started a new cycle. The best thing that we can do for the abusive parent is to pray for them to come to saving faith for only the Holy Spirit can ever cause change in their heart (Prov 21:1).
How we Dishonored our Heavenly Father
To honor someone that doesn’t seem to deserve honor is one of the greatest things that we can ever do but how do we do what seems impossible, especially if the parents abused us as a child? We must think as God thinks. Did you realize that God loved us and died for us while we were still His natural enemies, God-haters, wicked, evil sinners, who deserved only the wrath of God (Rom 5:8. 11)? How many of us were abusing God by sinning and dishonoring our Heavenly Father by lying, stealing, cheating, swearing, and hating others (murdering in the heart)? Not one of us deserved to have peace with God (Rom 5:1). No, we all rightly deserved the wrath of God (John 3:36b). There was nothing lovely about us or special about us that made God say “Wow, aren’t they precious, don’t they deserve to be saved, just look at my beloved children.” No, we were hostile toward anything that had to do with God because our natural, sinful mind is at war with Him and hated Him. You might think that is a bit strong but remember, we were once the children of wrath (Eph 2:3).
Listen to what Paul writes about the Ephesians before they were saved and to us before we were saved:
“you were dead in the trespasses and sins in which you once walked, following the course of this world, following the prince of the power of the air, the spirit that is now at work in the sons of disobedience—among whom we all once lived in the passions of our flesh, carrying out the desires of the body and the mind, and were by nature children of wrath, like the rest of mankind” (Eph 2:1-3).
Read that again. We were the children of (God’s) wrath, dead in sins, following the prince of darkness (Satan), and all sons (and daughters) of disobedience. We were most certainly not honoring God our Father. On the contrary, we were dishonoring Him to the utmost.
Now, think about parents who were abusive. They too are or at least were under this same prince of darkness and as Jesus once said, they, like we, will do the works of our father the devil before being saved. Jesus is clear about what the religious crowd was like and we too at one time: “You are of your father the devil, and your will is to do your father’s desires. He was a murderer from the beginning, and does not stand in the truth, because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies” (John 8:44). Before we were saved, we can just insert our name where Jesus says “you” and “your” because that was us!
How to Honor Abusive Parents
Now if a parent is physically or sexually abusing their children, they deserve God’s wrath but more than that, they deserve to go to jail, but what happens if that happened long ago and you are now an adult? How can you honor parents who abused you? Once again I say; it is not possible in our human strength. It takes the power of God to overcome our hatred for them. We should separate the sin from the sinner and hate what they did and not hate them. Besides, we are commanded to love our enemies  and pray for those who mistreat us, even if they were our parents (Matt 5:44a) so that we may be the sons and daughters of our Heavenly Father (Matt 5:44b). God loved us and died for us while we were still dishonoring Him. If He hadn’t, we’d still be destined for hell (Rev 20:11-15; Dan 12:2).
Also, think about this. Are they not saved? Think of where they will go and spend eternity…in a Christ-less, dark place with weeping and gnashing of teeth for all time. This will never change for them. Doesn’t it make you have compassion on them? You wouldn’t wish that on your own worst enemy would you? I would hope not. To honor those who don’t seem worthy of it (are we?!) we must not speak ill toward them, even though they have done evil. We must not degrade them in front of others or in front of them but be forgiving and look for something positive that they did. Surely you can think of something that they did for you; provided a home, food, clothing, and other things. And there is no time limit or expiration date on honoring our parents so we must do this, even into their old age, and yes, even after they die.
We can never, ever repay what God has done for us. We can never make right what our parents may have done wrong to us. So how do we make all these wrongs right? We don’t. Instead “never avenge yourselves, but leave it to the wrath of God, for it is written, ‘Vengeance is mine, I will repay, says the Lord.’ To the contrary, ‘if your enemy is hungry, feed him; if he is thirsty, give him something to drink; for by so doing you will heap burning coals on his head.’ Do not be overcome by evil, but overcome evil with good” (Rom 12:19-21). If you do good to them by honoring them, God will take that as honoring Him. If we try to avenge them ourselves then we are placing ourselves in the judgment seat of God. That is His job, not ours. Trust God for He will make all things crooked straight and if your parents abused you, forgive them as our Heavenly Father has forgiven us and pray that they repent and confess their sin, and place their trust in Christ. Praying for their souls is the godliest thing that you could ever do to honor your parents, even if they abused you and were not believers. By doing that, you will be honoring your Heavenly Father and by doing so, you “may be the sons and daughters of our Heavenly Father” (Matt 5:44b).
Related reading: Honor Your Father and Mother 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), copyright © 2001 by Crossway, a publishing ministry of Good News Publishers. Used by permission. All rights reserved.