Most scholars do not dispute the fact that Jesus was actually here on earth. There are writings about him that came from non-Christian sources (i.e. Josephus) that testify to his life and crucifixion. In other words, these writers had no particular love for Christ, and therefore had no reason to make up stories.
I myself have seen, in a Church in Rome, (Santa Croce en Gerusalemme), a nail that is said to be from the crucifixion, and part of the placard that Pilate ordered to be nailed above Christ's head on the cross. There are other relics pertaining to Jesus scattered all around the world, if one cares to look for them. They are real, concrete items. ***But,*** none of these relics alone can give a person faith in God, nor in His Son, sent from heaven. For a person who already has faith, a chance to view these relics is a beautiful experience.
Ryan, my advice to you is to pray for your brother to open his heart to God. His questions to you seem negative, but they just may be a sign that he is actually thinking about God! See if he is open to reading a book written by a scientist, making the case for God. "The Creator and the Cosmos" by Hugh Ross helped my technical-thinking husband a great deal. Mr. Ross is not Catholic, but it is on the whole a good book.
May the Holy Spirit lead both you and your brother right to the place you should be!
