What are the sins that don't lead to death?

The true Christian Church has always referred to "sins leading to death" as "mortal sins", which obviously means "leading to death", as in a "mortal wound". The page refers to spiritual death, loss of grace, not biological death. In the next verse, John goes on to say that sins not unto death are easily forgiven by a simple prayer, but that deadly (mortal) sins cannot be forgiven that way. Which is why the true Christian Church refers to such lesser sins as "venial", which means "easily forgiven". Forgiveness of mortal sins requires something more, and Jesus revealed how such major sins can be forgiven when He breathed upon the apostles, the first priests of His Church, indicationg a special empowerment by the Holy Spirit, and then told them, "Whose sins YOU FORGIVE, they are forgiven them". (John 20:22-23)