Answer:
Protestants believe in scripture only..meaning they go by what the bible says alone...which is different then what Catholics believe who also go by what different popes have said over the years along with the bible Mormons and others also use other books they believe a modern day prophet wrote as added information to the bible. Protestants do none of those things.
Protestants believe in the Trinity..that God is made up of three parts...God the Father, God the Son and God the Holy Spirit. That we are all sinners and since sin cannot enter Heaven God sent His Son to pay for our sins. When a person accepts that free gift and repent of their sins, they are saved, filled with the Holy Spirit and free from the bondage of sin. They believe Jesus will one day return to judge the living and the dead in the Second Coming. They believe Jesus died for their sins, rose from the dead and currently is sitting at the right hand side of God.