First of all what exactly is free will is a difficult question and I have not come across precise definition of free will. Also as Nitai ji has pointed out whether there is no free will in CV is something you can say for sure. So I don't how you are so confident that free will does not exist in CV. In a strict sense omniscience of God and free will are not compatible with each other because if all future is already known to God then what exactly is free to choose. However, some people use compatibilist theories of middle knowledge etc to get over this problem. 188.8.131.52/entries/freewill/ Anyway Malati ji, this issue was debated before and there was no conclusive evidence that CV has no room for any kind of free will. I hope Nitai ji can comment on this.
Another thing is Sivarama Swami never talks about specific claims about the tradition that can cause difficulty like divinity of Sri Chaitanya, miracles attributed to him, panca tattva theory, yugas and their inconsistency with empirical evidence, cosmology of the bhagavat etc etc. If you argue generically, it is possible to do decently with almost any faith. However, atheists know a lot about Christianity in detail so they argue on specific points like belief in resurrection etc that are based on shaky foundations. CV is not popular enough that people know the in and out of it.
William Lane Craig certainly is good when he is debating on generic topics. However, on specific topics like resurrection of Christ www.freewebs.com/deityofchrist/resurrection-debate-transcript.pdf this debate www.youtube.com/watch?v=FhT4IENSwac&fb_source=message (written pdf and video both are availble), he really flounders because the opponent is well verses in the subject. The greatest debaters for believers are people who were believer themselves before. Therefore, they have explored the tradition in detail and know the specific claims that are hard to believe. Why doesn't Sivarama Swami start with the claims that evolution is false and we never went to the moon? Then he will lose the debate, right?