The Bible tells us that everyone who believes in Jesus is a Christian. But what does belief in Jesus really mean?
Before concluding that someone is undoubtedly a Christian, we should at least determine which Jesus a person believes, and what type of belief he or she holds. Let's expand on these two very crucial points.
First, Christians must make sure that anyone professing to believe in Jesus is actually referring to the Jesus Christ of the Bible. The Apostle Paul, in 2 Corinthians 11:4, warns us about individuals who preach counterfeit Christs. Take, for example, the New Age Jesus who supposedly journeyed to the Far East, where he allegedly became a master of the occult. Then there's the Jesus of Mormonism, who supposedly belongs to a gallery of gods and goddesses. And, of course, the Muslims believe in yet another Jesus, one who simply numbers among the many so-called prophets of Allah, the God of Islam. But of these and other assorted Christs, only the Christ of Scripture is recognized and accepted by true Christians. Let us, therefore, take care to find out which Jesus a person believes in before we pass any judgment.
This leads me to point number two -- that a person also needs to exercise the proper type of belief. For example, someone who holds to an accurate view of who Jesus Christ really is, and what the Bible says about Him, still needs to do something with his or her belief, and not simply stand by on the sidelines. True Christian belief is demonstrated through action. It isn't merely a passive acceptance of a set of doctrines (cf. James 2:19), but an active and dynamic relationship with Jesus Christ, trusting Him as personal Lord and Savior (Rom. 10:9; Titus 2:13). Christians are sinners saved by grace; and until a person has developed a saving relationship with the Jesus of the Bible, he or she, unlike true Christians, still remains dead in sin and so is it even with the True Christian who does not confess his sin directly to God and or through the Priest (who is anointed by God to forgive sin). In summary then, true biblical belief involves not only knowledge and agreement, but also trust in that through His Sacraments we come To demonstrate what we truly believe and this includes that we must trust in Jesus Christ alone for eternal life.