You absolutely should add "I Believe" if, without that phrase, you would be making a claim of fact that you cannot be certain is true.
Do you have scientific proof that people should eat apples for their health? Without some medical studies, you make a misleading statement to say "people should eat apples for their health", you are implicitly lying to people by implying that this is a known fact.
However, saying "I believe people should eat apples for their health" is a truthful statement if you truly believe that.
So is "I believe eating apples is a gateway to heroin use, promiscuity, harsh music and the sexualization of astronomy".
I can argue that eating apples almost never sexualizes astronomy, but I can't argue that you don't believe what you say you believe.