Creation: It is scientifically impossible for Nature to have made itself.
Here is really the gist of it: Ray is so determined to prove God's existence that he will blatantly ignore what actual scientists (and the kicker--scientific evidence!) have to say about it.
Conscience: Every culture, from the beginning of time, has a God-given and society-shaped knowledge of right and wrong.
Bullshit. Every culture has a different view of what's right and wrong, and anthropologists can easily scientifically explain that. But if you won't let scientists tell you why you're wrong, I guess you won't let anthropologists either.
Commandments: God gave us the Ten Commandments (which are confirmed by the conscience) to show us that we need His mercy.
Muhammad gave us the Koran to show we need Allah's message.
And the Ten Commandments aren't confirmed by conscience. I don't feel anything wrong when I say "God" or "Goddammit all to hell!" I don't feel anything wrong when I disagree with my parents and express that. I don't feel anything wrong with my pantheist belief and my nonbelief in God. I don't feel anything wrong when I treat Sunday (or Saturday) like any other day. I don't feel anything wrong when I tell a necessary lie. And you know what, most people, particularly those from a non-Christian culture, don't either.
Conversion: We can come to know God simply by obeying the gospel.
Yes, and reading the Bhagavad Gita can help you know Krishna and thus proves that Hinduism is the true religion.