One of the questions I’ve heard from believers is that if there’s no God then what is the ultimate purpose to life? In extreme cases, this might be “why go on living at all?” This isn’t really an argument, per se, but it is something that might make a person unwilling to consider an argument from an atheist.
Many people who are already atheists (agnostic or otherwise) may be tempted to respond with “there is no ultimate purpose.” While this may be true, it’s probably not likely to be effective when talking with a believer. Instead, consider asking “if you could choose any ultimate purpose for your life, what would you pick?” This way of phrasing the question instead of something like “what ultimate purpose do you think you have?” gets around stock answers like “to praise and worship God.”

When you ask what a believer would choose, they are hopefully forced to consider the question the same way an atheist might. Even if they fall back on the stock answer, you can push further, “would you really choose to be an eternal sycophant or even a slave with no reason to exist other than to praise an already infinitely powerful being?” Ask if that really sounds like something a loving god would even want to inflict on someone. The goal here isn’t to try to dismantle an argument (because, again, this isn’t one) but rather to force them to consider questions they might not have before.
Assuming you make any headway with this, eventually the theist may ask what purpose an atheist can have. This is where is gets a little trickier because there isn’t a single answer for everyone. I wouldn’t suggest starting with “whatever purpose you choose for yourself” as that’s unlikely to be a satisfying answer and instead try to relate to them. Share what motivates you, personally. For me, I might share any of these possibilities.
- “To make the most out of this life because it’s the only one I can know for sure that I have.”
- “To do my best to improve the life of at least one other person.”
- “To believe as many true things and as few false things as possible.”
Eventually you will likely get to the concession that there is no ultimate purpose to life but that is actually a good thing. If your purpose was determined by an all-powerful entity, then what freedom would someone have to decide for themselves what they want? Why give us free will if we can’t exercise it in the most important decision of all?
The idea that we can choose a purpose for our lives, and even change our minds about it later, is the ultimate expression of what it means to be human. Without being shackled by a purpose dictated to us by others that supposedly comes from a god, we are truly free to decide what to make of our own lives.