First of all, we must admit that there are occasions in Scripture where slavery is practiced and seemingly endorsed under certain circumstances and in certain contexts. To try and wiggle out of that fact is a mistake because it feels like spin and indeed it would be exactly that. However, this does not mean that just any model of slavery was viewed as acceptable in Scripture. It was not. Scripture reveals a very specific model of slavery practiced in the context of the ANE and in ancient Rome. That much is true. However, Christianity introduced strict ethics around how even that model was executed. That said, slavery is not the subject of this post.
Now, for starters, keep in mind that this is a tactic from the objector to disprove Christianity. It is not the case that the objector really is saying to you, “look I would embrace Christianity if it wasn’t for the fact that God allowed actions that I consider immoral. If you can show me that God is not immoral, I will follow him, cross my heart and hope to die.” Treat this objection for what it is: a disingenuous excuse to exercise the universal practice of self-justification. Think about it this way: you have before you a totally depraved sinful human being pronouncing moral indictments against God. This is blasphemy! Part of our problem when dealing with objections like this is that we do not consider and very often fail to appreciate the seriousness of the sin from which they arise. Any objection that portends to judge God is particularly pernicious and should be dealt with accordingly. I have no difficulty telling people who make this objection that they are guilty of blaspheming God. It is not polite not to tell them the truth.
First, the objector has no moral standing to condemn slavery if there is no God. That S/he does so is proof that their own belief is irrational. The reason this belief is irrational is because a world of chance contradicts a world of absolute morality. A world of chance cannot produce a world of absolutes. A system that involves obvious contradictions is irrational. Second, when pressed far enough for a rational grounding of morality, the best they can do is say they do not know where objective morals come from but they just know that something like slavery is wrong. This too is irrational because there is no rational grounding for their belief. They will bounce from one theory to another, each one failing to provide the grounding they so desperately need. And in the end, the shoulders will shrug and even though they do not know, they will insist on knowing that we don’t need God for absolute morality.
Since the objector has no grounding for morality in general, they have no objective basis from which to condemn slavery in any expression whatever, let alone the slavery mentioned in the Bible. This means their objection is not sustainable. You can reject it and be within your right not to answer it. The judge of logic would say: objection overruled.
Now, let’s take a different perspective to the objection. God as creator has every right to treat every human being as a slave if he so chooses. After all, every human has rebelled against his Creator and deserves to be treated much worse than a slave. So the idea that slavery is immoral necessarily implies that human beings have a right to be treated better by God than slave treatment, and that is patently false. We do not. We deserve nothing but condemnation and wrath from the hand of our Creator. It is only due to God’s grace and loving kindness that our experience in this life has any pleasure whatsoever, or lessor degrees of displeasure than we currently experience or have experienced over the course of our lives. And that is just as true for the slave as it is for the free.
A lot more could be said about this argument but I will leave it here for now. This is enough to demonstrate that the moral objection to God over slavery fails to meet its obligation as a true objection and therefore, any rational person ought to abandon it.
Disclosure: This article does not deal with the morality of modern forms of slavery such as that practice by early American society. The aim is purely apologetic in nature and the intention is to help Christians deal with a very specific and very common objection to Christianity.