system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: the Holy Spirit in Christianity

I literally went to Sunday school for a decade growing up and just realized I still have no idea what the heck the Holy Spirit is or how it's distinct from the other parts of the Trinity.
gpt
That'll depend somewhat on your denomination, but AFAIK the most common teaching is that the Holy Spirit is the personal presence of God in a believer. Sort of like an additional conscience, untainted by sin, guiding believers to salvation. The Holy Spirit entering the body is what baptism represents, whether the church uses oil, dirt, water, etc.