Those things are of man's invention and traditions of men. The gospel of Christ is really quite simple - God sent his only son into the world, to live as a human and to provide the example of how other humans should live. But men didn't want God among them, so they killed him, just as God know in advance that they would. But God's power overcame the last obstacle, which is death, by raising Jesus from the dead after 3 days. God calls all people to be his people, and he will be our God - if we believe in His son, Jesus the Christ, confess that we believe on him to others and repent (turn our backs) from our sins, and are buried in water (immersed) in the name of the Father, the Son and the Holy Spirit for the forgiveness of our sins. THEN and only then are we 'in Christ', by being buried with him in baptism (see Romans 3 and 6, as well as the examples of those early Christians in the book of Acts). He then calls us to remain faithful to our commitment to Jesus Christ until we die, knowing that we will sin but having confidence that the blood of Christ washes us clean if we confess our sins to him. The early church reminded themselves every first day of the week (Sunday) of Jesus' sacrifice, death, burial and resurrection when they came together to eat the bread and drink the wine, symbols of his body and blood. If we will do this every Sunday, 52 times each year for as long as we live, we will not forget what God has done for us.