That’s not a friend. Friendship is between approximate equals and requires respect and trust. He does not trust or respect you. He looks down on you for your age and ignores your valid arguments because of it. If you have any choice in the matter, get away from this person and find people who, even if they disagree, will do so from a place of reason and respect. Do not be fooled into thinking someone is a ‘friend’ just because you interact with them regularly.