I discussed it with a creationist friend once. He simply stated, "I don't believe in evolution, it doesn't make sense" as we finished lunch. I calmly and politely asked if it had ever been explained to him by a scientist and he said that he hadn't. I said, "would you like me to explain it to you to the best of my ability and see what you think?" and he said yes as another friend (who probably would have been condescending about it) tried to jump in and another told him to wait and see how I did.
I had this walk back to give my best effort, and we had all had a few beers.
from: Main St to: Broad St - Google Maps
In this short trip, I explained how random mutation leads to favorable and unfavorable genetic traits, and that those traits that increase an individual's chance of procreating offspring who survive to sexual maturity are considered to be selected for, and those who hinder it are said to be selected against. Over a grand time scale, these little changes add up, and a basic intro of how speciation occurs when previously compatible groups develop in different enough environments that their set of genes is incompatible with the other group(s.) Through billions of years of changes, a little bit at a time, we went from self-replicating molecules in the primordial sand to celled organisms, to multi-cell organisms. We're separated from apes by tends of millions of years, you can't expect a monkey to have given birth to a human or vice versa because it can't work that way. I pandered to his religion a bit since debating that is none of my business, and said something like "Isn't it a more beautiful testament to the awesome power of God and his infinite wisdom to say that he set the universe in motion, planets and stars came together, and eventually his "forming us out of clay" was the spark that started life in the primordial ooze that started life as we know it," than if he just pointed his finger and wea appeared?
He looked at me with a bit of bewildered, and said "wow, nobody ever explained it to me like that. I think you're right."
A few weeks later he was discussing philosophy and theology with someone and I overheard him say "Yeah, I think God created us, and he used evolution to start life and get it to where it is today." I had a shit eating grin on my face like a parent whose kid just won the spelling bee.