None of them are rational.
The first is just a bit of special pleading. It amounts to "Order needs an explanation except when it takes the form of God" Well why exactly should "God" get a special exemption other than the fact that God's existence is the desired conclusion ?
The second is equally bad. God would equally appear to be "intelligently designed" and "purpose driven". So either we have an infinite regress or we recognise that we ought to look for other explanations.
The third is just silly. Why should the bare existence of nature imply the existence of anything supernatural ?
To be honest, anyone who falls for ideas like these is not a great thinker. Flew may have been a significant figure in the past - but he certainly doesn't seem to be now. So his "conversion" is hardly the significant event that some would have you believe.
To me the main significance is the shabby dishonesty of publishing the book under Flew's name when he didn't write a word of it - and a significant part was written by someoen who doesn't even get a credit.
It is written "by their fruit you shall know them". It seems that Varghese is just one more bad apple from a rotten tree.