You concede that the human body is designed with involuntary 'actions' (do you mean functions?). The responses of the body (variously manifesting as stress, anger, lust etc.) are determined by hormones. If your cortisol is high, for example, you will feel anxious. Are you arguing you have control of your own hormonal system?
This is true
but we decide what to wear in the morning, what college we want to go to. what we want to eat, drink, when we want to go to bed. What we want to watch on tv, what movie we want to see or what game we may want to watch. We even chose what religion we wish to follow,
when it comes to God, God convicts us of sin, then convinces us of the truth of Gods solution for sin, and his offere of salvation, we chose to continue in unbelief and remain lost, or as the tax collector to fall based on our newfound understanding of our eternal situation and hopelessness and call out to God. Because God has convinced us of his truth.