Why does he need to explain anything to anyone?
As long as he hasn't been in trouble with the law and lives his life within the context of the law he doesn't owe anyone an explanation for any of his viewpoints. The Constitution and our Bill of Rights provide this for every citizen of our country.
Outside of maybe a Politician or Judge, who have the ability to change/enforce our laws, no one owes an explanation to anyone for their respective opinions or points of view.
Sadly this fact has been lost on far too many people today.