Some lefties are fine, as long as you stay off the politics. It can lead to boring conversations, but that’s better than heated, frustrating ones....and much better than fisticuffs. lol Sadly, my son veered way to the left because of his dopey university friends. I thought he was going to be ok, as I steered both him and his sister away from university. They were home-schooled until higher grades, then to private Christian schools. The lefties got my son, but my daughter is as “right” as they come.
As has been stated by many including Mark Levin, as a young adult they were dims as the got older they became pubbies, hope this happens for your son.
Never stop praying specifically for Godly men and women to come into his life. Parents can't tell their grown young adults a thing; but outsiders can exert great influence. Happened to us, in miraculous ways. Never stopped praying.