Of course it would all be futile if Jesus was just a great teacher. There would be no virtue in such a sacrifice from God for our sins so why then the resurrection. The resurrection and His testimony demonstrate that Jesus was and is and will be the Son of Man who Enoch Enmendurana in Sumeria described as being there always with God. Jesus is the one through whom God made all things that exist and He was always known for righteousness and lived in a body in Roman times and never sinned and so was a perfect sacrificial lamb for sin and when He died God therefore saw it as enough and raised Him to life again on the third day to be High Priest over God's House.
