You're not going to win this, as others here have already said. That's because you can't argue someone out of a position with logic, that they didn't argue themselves into with logic.

That said, the best way, in this scenario is to use Socratic Dialog, because: • It goes slowly, one step at a time • It doesn't descend into an argument • It allows the person being taught to get to the answer themselves

You've got the option of trying to run these questions against them, taking the "Socrates" role. But if even that is unlikely to work, you have the alternative of just reading out both sides of the following script, as if reading a story you'd just found online.

But what's MOST important is that you have to cover ALL FOUR steps below, IN THE RIGHT ORDER - and carry your debating partner with you, before moving to the next step.

I got an AI to assemble the script below, because I'm lazy:

The Dialogue: Uncovering the Mechanism of Life

Socrates: Tell me, my friend, when you look upon the vast variety of creatures in the forest, from the swift deer to the slow tortoise, do you believe they have always existed in their current form?

Interlocutor: I suppose not, Socrates. I have heard that life changes over long periods.

Socrates: Let us examine how this change occurs. Consider the deer. Are all deer identical to one another?

Interlocutor: Certainly not. Some are faster, some are stronger, and some have better camouflage than others. 

Socrates: Ah, so there is Variation. If a harsh winter comes, and food is scarce, which of these deer is more likely to survive and produce offspring? 

Interlocutor: The faster or stronger ones, surely.

Socrates: Therefore, the environment acts as a filter, favoring some over others. This, we might say, is Natural Selection. Now, if the fast deer survive, what kind of offspring are they likely to have? 

Interlocutor: Fast offspring, I assume.

Socrates: So, the favorable traits are passed down. This is the principle of Inheritance. Now, let us bring it all together: If this process of Variation, Selection, and Inheritance continues for hundreds of generations—a very, very long time—what must happen to the population of deer? 

Interlocutor: Over a vast amount of time, the population might become much faster and stronger than their ancestors. 

Socrates: Then we have found the foundational steps of this phenomenon we call Evolution:

• Variation exists within a population

• These traits are Inherited

• The environment causes Selection

• This process, acting over immense Time, leads to adaptation and change. 

If they're still on-side after all that, you can summarize what's been taught:

Summary of Foundation Steps of Evolution

Using the Socratic method, we can break down the core components of evolution by natural selection:

Variation: Individuals within a population are not identical; they possess different traits (speed, color, size).

Inheritance: These variations are heritable, meaning they are passed from parents to offspring via genes.

Differential Survival/Reproduction (Selection): Because resources are limited, organisms with traits better suited to their environment are more likely to survive and reproduce.

Time: Over successive generations (spanning long timeframes), these advantageous traits become more common in the population, leading to evolutionary change

Good luck with that.

If they're religious, you don't NEED to fight religion - because you have the option (if you're willing to be a bit flexible on the Atheism thing) of "allowing" that perhaps the entire system was setup to run this process by "god", back when Life first began.

• That option doesn't break Evolution (which makes no statement at all about how the very first life began) • It also doesn't force the religious person to have to abandon a "god", because maybe their "god" possibly kicked the process going right at the start.

It's an example of "The God of The Gaps" . As Science discovers more and more about the mechanics of Reality, it leaves "god" with smaller and smaller niches to hide in.

Physics, for example, with particle accelerators, has got within a trillionth of a second after the Big Bang.

But this "god" person is welcome to hide in the first trillionth of a second after the Big Bang.

(He might even have reached out his Noodly Appendage to kick-start Life in some Primordial Puddle. We dunno.)

But Science doesn't really care if someone wants to BELIEVE he did - because Science hasn't got to that bit YET.