There is a tragic irony in that one of the most common arguments in atheism is the evil God argument. There's even a whole website dedicated to showing all the places in the Bible atheists consider "evil" called evilbible.com. The irony of the argument is that, while it is emotionally effective, it's actually self refuting.
See, if atheism is true, then all allegedly evil acts in the Bible, if they even occurred, are not objectively evil, but rather, undesirable to the atheist making this particular argument. If, for example, Evolution is true, then the violence in the Bible is just a bunch of dead monkeys who once killed other monkeys. They don't remember what they did to their victims, their victims don't remember what they did to them, so really, it was just a bunch of irrelevant fighting that modern atheists don't like.
Obviously, Evolution is just the most common religion an atheist might follow, so that is just an example, but the truth is, there are a grand total of zero atheistic moral systems that objectively bind anyone, much less a bunch of dead people, to any standard of "good" or "evil". And many atheists are actually waking up to this fact. The very week this article was initially written, I had an atheist flat out tell me that morality is subjective. But if morality is subjective, then God cannot be evil, and therefore you cannot use the "evil God" argument to disprove the Bible.
But if God exists, then morality is not only objective, but is set by Him. Yet, we don't get to judge Him. He judges us. And that, really, is the problem atheists have. Every in-context verse atheists cite to suggest God is somehow evil is a verse in which He judges sin. And atheists, of course, are sinners. That's not to say Christians aren't, it's just that we now understand the motive. What sinner looks at the punishment for sin and thinks it's good? It's a punishment. It's not supposed to be a reward. And so there are two responses. The first, which of course is the atheistic response, is to double down, not only justifying one's own sins, but disputing the justice of the punishment.
But the wise response is to look at the punishment and realise that this is how seriously God takes sin. If this is what we deserve for sin, sin must be rather awful in His Holy eyes. Thus, we ought to repent, and submit to Him. Thankfully for us, this is a lot more effective than, for example, apologising to the government for breaking their laws. If you break the law, you can show as much remorse as you want, you're probably still getting punished. But God, beyond all imagination, hears the prayers of the penitent.
See, though sin requires punishment, it is not within God's will to deliver it. Instead, He sent Jesus to receive it for us. Jesus died so that we might be forgiven by faith. Confess Him as Lord, and believe in your heart God raised Him from the dead, and no matter how severe a punishment you deserve, you will instead receive eternal life! That's how evil God isn't.