How easily do you get offended? Or insulted? Slighted?
Common or rare?
As Eleanor Franklin observed, "No one can insult you unless you agree with them."
Many, especially those who are emotionally "thin skinned," seem especially on the lookout for circumstances in which they can feel some sort of justifiable rage, anger or at least irritation, based on the behaviors, beliefs or opinions of others.
It's a convenient source of angst.
This is one of those common social subluxations that you have complete control over. Being "offended" is merely a choice. What someone else believes has little meaning other than what you give it. Choosing to make it an attack on your beliefs is just that, a choice.
Hold fast. Know what you know. Believe what you believe. Assume they will come around. As you did. They're just not ready yet. Smile. Their time will come. Bite your tongue.