You sometimes hear someone claim to be “spiritual but not religious” because they don’t need “all that doctrine.” St. John in his first epistle would beg to disagree. It is exactly “doctrine” that grounds our spirituality, he would assert. Who is the liar? Whoever denies that Jesus is the Christ. Whoever denies the Father and the Son. If one denies Jesus is the Christ then you are cutting off the history of salvation showing God’s providential care of the Chosen People in concrete human circumstances. If one denies the Father and the Son then Jesus is just a nice guy that we can choose to admire or not. As the Son of God he claims us as children of God ushering us into eternal life.