The Christianity which is from above will always be known by its fruits. It will produce in the person who has it repentance, faith, hope, love, humility, spirituality, kindness, self-denial, unselfishness, forgiving spirit, moderation, truthfulness, hospitality, and patience. The degree in which these various graces appear may vary in different believers. The germ and seeds of them will be found in all who are the children of God. By their fruits they will be known. Is this your faith? If not, you should doubt whether it is authentic.