I have glorified thee on the earth: I have finished the work which thou gavest me to do. John 17:4
Jesus spoke this in the garden, the work which God gave Jesus to do was finished in that God was glorified on the earth that now people knew who God was and that Jesus established His Kingdom on earth. The work in which Jesus was to do was finished, and His death on the cross was not work that Jesus was to do, but was something that God had to finish in order that we will have eternal life. Through Christ’s death and resurrection God was finishing the work that He would have done by sacrificing His Son as a sin offering for us once and for all. We believe in Christ through the word of the Apostles we have atonement because of God’s Work on the cross. So all who believe in Jesus also believe that God is and always has been, thus God is made real to us through His Son, and our sins are taken away because of that belief in Jesus Christ and God the Father.