I'm sorry to hear you're feeling this way. It's actually quite common to feel lonely or isolated, even when surrounded by others. These feelings can be exacerbated when there's a perceived gap between our own internal experience and what we think others are experiencing. This phenomenon is often referred to as "social comparison," and it can cause a great deal of distress when we believe that others are happier, more successful, or otherwise better off than we are.
In your case, the perceived discrepancy might be related to your feelings about your sexual orientation and the difficulty you're experiencing in reconciling these feelings with your religious beliefs. This is a complex situation that many people struggle with, and it's completely normal to feel lonely and misunderstood when dealing with such deeply personal issues.
It's important to remember that everyone has their own struggles, even if they don't show them on the surface. People often present a more positive version of their life to others, whether in person or on social media, but this doesn't mean they aren't dealing with their own challenges.
That said, it's important to talk to someone about what you're going through. This could be a trusted friend, family member, or a mental health professional. You don't have to go through this alone, and there are people and organizations out there who can offer support.