I'm glad you and your wife are still getting along despite your difference of opinion.
The gist of your brother's argument is that God is beyond logic and rational thought, and cannot be understood or accepted with these approaches alone. Therefore you must use your emotional side when considering Him.
The first part is an admission that God doesn't make conventional sense even to your brother. He himself has tried to reconcile the whole idea, and failed. The reason he's still a believer is the emotional experiences he's had while worshipping. He's probably attributed them directly to God. The power of these experiences, regardless of their source (my guess: himself, with the help of semi-hypnotic preachers) overrides the apparent irrationality of belief.
To use an old, casually religious expression, it's a case of "there but for the grace of God go I". If you were to go to a service with him and have a "religious experience", knowing full well that your own brain could have produced it, it would still be hard for you to dismiss the idea of God so easily. Don't think that your brother is somehow weak because his experiences have admittedly affected his judgement. His emotional state is working against his own logic. That's hard on anyone.
I agree with your brother in one way. We must all be open to the unknown, or as he says, "leave a space for Him to reveal Himself," if He exists. However, that does not mean falling to your knees as soon as something extraordinary happens to you. It means honestly examining all the evidence, interior and exterior, and comparing different explanations.