It depends on what you mean by “Jesus.” A god who came to earth and rose again? I would question why you would believe that if you’re not spiritual. But a Jesus who hand an interesting take on Judaism, flirted with messianic ideologies, and who apparently impacted someone who would eventually deify him, well, we’re pretty sure that guy existed, we just don’t know much about him.

As to sin, well, that would depend upon the creation story, which is incompatible with what we know about earth’s evolution. And here I would ask, “Why do you need sin?” We all ask the bigger questions about “right and wrong,” but at our everyday level, we know to “do no harm.”

God, heaven, afterlife... it all depends on how you define them. Do you do so against the backdrop of Christianity? That would put you back in the religious camp. But to consider the bigger questions, and use the term “god,” “heaven,” all that, as long as you’re not using those terms to bring harm, I see nothing wrong with it.

People just say that so they don't offend anyone

Well where do they think those ideas come from? Organized Religions. I think they just want to make themselves sound more credible.

It is semantics. Maybe they say they are not "religious" because they think they have a "personal relationship" with the invisible man in the sky. These are often the pious. By most people's definition they are religious. Though their piety, delusional thinking, and self-rightousness leads them to think that they are something beyond that...

Just in case? Or they find some confirmation to their bias in it.

Many people do not go to church or temple or mosque and still believe. that does not make them religious, it means they have a belief system.

Morons

What? Where?

Liars?