Excerpt from John MacArthur's article of the same title.
Here are some questions that need to be answered biblically:
Do we receive Jesus as Lord and Savior, or as Savior only?
Some say a person who refuses to obey Christ can still receive Him as Savior. They teach that the gift of eternal life is available by faith even to one who rejects the moral and spiritual demands of Christ. They accuse others of teaching "lordship salvation," implying that it is novel to suggest that submission is a characteristic of saving faith.
Until relatively recently, however, no one would have dared suggest a person can be saved while stubbornly refusing to bow to Christ's authority. Nearly all the major biblical passages calling for saving faith refer to Jesus as lord (cf. Acts 2:21, 36; Romans 10:9-10).
Is repentance from sin essential to salvation?
Some say that turning from sin is a human work and therefore cannot be part of salvation. To accommodate the biblical call to repentance, they redefine repentance as nothing more than a change of mind about who Jesus is.
Biblically, however, repentance is a total about face--turning away from sin and self and unto God (cf. 1 Thessalonians 1:9). That is no more a result of human effort than faith itself. Nor is it in any sense a pre-salvation work required to prepare a sinner for salvation. Real repentance is inseparable from faith and, like faith, is the work of God in a human heart. It is the response God inevitably generates in the heart of one He is redeeming.
What is faith?
Some say faith is merely believing certain facts. One popular Bible teacher says saving faith is nothing more than confidence in the divine offer of eternal life.
Biblically, however, the object of faith is not the divine offer; it is the Person of Jesus Christ. Faith in Him is what saves, not just believing His promises or accepting facts about Him. Saving faith has to be more than accepting facts. Even demons have that kind of faith (James 2:19).
Believing in Jesus means receiving Him for all that He is (John 1:12). It means both confessing Him as Savior and yielding to Him as Lord. In fact, Scripture often uses the word obedience as a synonym for faith (cf. John 3:36; Acts 6:7; Hebrews 5:9).
What is a disciple?
In the past hundred years or so, it has become popular to speak of discipleship as a higher level of Christian experience. In the new terminology, a person becomes a believer at salvation; he becomes a disciple later, when he moves past faith to obedience.
Such a view conveniently relegates the difficult demands of Jesus to a post-salvation experience. It maintains that when He challenged the multitudes to deny self, to take up a cross and follow Him (Mark 8:34); to forsake all (Luke 14:33); and to leave father and mother (Matthew 19:29), He was simply asking believers to step up to the second level and become disciples.
But how does that square with Jesus' own words, "I did not come to call the righteous, but sinners" (Matt 9:13)? The heart of His ministry was evangelism, and those difficult demands are evangelistic appeals.
Every believer is a disciple and vice versa. A careful reading of Acts shows that the word disciple has been a synonym for Christian from the earliest days of the church (cf. 6:1-2, 7; 11:26; 14:20, 22; 15:10).
What is the evidence of salvation?
In their zeal to eliminate good works as a requirement for salvation, some have gone to the extreme of arguing that good works are not even a valid evidence of salvation. They teach that a person may be genuinely saved yet never manifest the fruit of salvation--a changed life.
A few have even taken the absurd position that a born-again person may ultimately turn away from Christ into unbelief, deny God, and become an atheist--yet still possess eternal life. One writer invented a term for such people: "unbelieving believers"!
Scripture is clear that a saved person can never be lost. It is equally clear that a genuine Christian will never fall back into total unbelief. That kind of apostasy proves an individual was never really born again (1 John 2:19).
Furthermore, if a person is genuinely saved, his life will change for the better (2 Corinthians 5:17). He is saved "for good works" (Ephesians 2:10), and there is no way he can fail to bring forth at least some of the fruit that characterizes the redeemed (cf. Matthew 7:17). His desires are transformed; he begins to hate sin and love righteousness. He will not be sinless, but the pattern of his life will be decreasing sin and increasing righteousness.
You need to settle these critical questions in your own heart. Study the gospel Scripture presents. Listen with discernment to every speaker you hear. Measure everything by the Word of God. Above all, make sure that the message you share with unbelievers is truly the gospel of Christ.