Does your friend have an example of a highly complex thing that was not designed? His example from evolution is not a good one. Evolution involves change that happens to already-living species. No one denies (as far as I know) that living things evolve through the processes of mutation and natural selection. That is not the question. The question is how did life itself come to exist? Evolution does not help to explain the origin of life itself. Please break this to your friend gently, but it appears that he does not know what he is talking about if he claims evolution proves that complex things are not designed. What is the origin of life? Evolution is not a theory of origin of life. Evolution is change occurring to an already-existing complex thing whose origin needs to be explained. Again, to say that a thing can be complex without being designed is an empty statement unless one can give an example.
Is your friend arguing that Christians cannot make their own decisions? What is his evidence for this? How does choosing to become a follower of Christ mean that we no longer make our decisions? Jesus called his followers again and again to make decisions. Christianity proposes the existence of free will. True, biblical Christianity does not involve forcing anyone to do anything. A person decides for themselves whether to become a Christian and whether to obey the teachings of Christianity. In fact, decisions that are forced are not decisions based on faith and in Christianity, salvation is based on faith. Maybe your friend thinks that once a person becomes a Christian, their decisions are made for them. If so, who is making that decision for them? This really does not make sense. Perhaps what he is saying is that if I become a Christian, then what is moral and what is right and wrong is no longer decided by me, but by God and I do not like this. The problem with this is that if morality is real at all, then it is an objective thing and how can the decision of one person determine what is right or wrong? In this system, objective moral reality evaporates. In my opinion, your atheist’s second point is a red herring argument.