I never considered a difference of opinion in politics, in religion, in philosophy, as cause for withdrawing from a friend.

Agreement is a thin foundation for friendship, and it is rarely what you actually value in someone. What you value is how they treat you, what they notice, whether they show up when it matters. When a difference of view becomes reason to drop a person, you have made your own opinions the price of your affection. That leaves you with company that only echoes you.

Keep one friendship where you disagree about something that matters to you both. Ask them a question about it instead of arguing, and let the answer stand without being corrected.