Yes there is; it is a person who has genuinely accepted the person salvational offer of Jesus Christ.
THEN the improvement in life begins. Some people in that situation may look very untraditional on the surface. But the Lord knows that this is only the surface. They will not be excused, but they will by the Lord’s promise be forgiven and saved.
Talk in the vein that we must make ourselves Christians is very vain and very misleading. All we can do is find ourselves learning to assent to the reach of the Lord.
Obviously you’re right. But how do we know about the saving life of Christ if we don’t believe in the God-breathed Word of Life? Everything we know and believe about the redeeming love of Christ comes from the written word empowered by the Holy Spirit. Any attempt to deviate from the verbal and plenary inspiration of scripture will ultimately result in heresy and unbelief.