Willful choice is one of those things everyone knows they have through direct experience. Do you deny that you chose to reply to his post rather than remaining silent? Do you deny that your choice was an act that you undertook because you willed it? Why people deny things that are so blatantly obvious is an utter mystery to me. Apparently it’s not something restricted to the religious.
Not only should you know this from your own personal experience but you should likewise be able to pick it up from the way that people respond to you. They treat you as if you have free will. And you do the same when it comes to your interaction with them. You treat them as if they have free will.
Do better.