When comes to understanding what it means to be a Christian, the Bible is the ONLY source.
"Jesus said to him, 'I am the way, the truth, and the life. No one comes to the Father except through me.'" John 14:6
"For I am sure that neither death nor life, nor angels nor rulers, nor things present nor things to come, nor powers, nor height nor depth, nor anything else in all creation, will be able to separate us from the love of God in Christ Jesus our Lord." Romans 8:38-39
"Therefore also God highly exalted Him, and bestowed on Him the name which is above every name, that at the name of Jesus every knee should bow, of those who are in heaven, and on earth, and under the earth, and that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father." Philippians 2:9-11
"Then I heard what seemed to be the voice of a great multitude, like the roar of many waters and like the sound of mighty peals of thunder, crying out, 'Hallelujah! For the Lord our God the Almighty reigns.'" Revelation 19:6