What is assurance? How do you know if you have salvation and are a member of God's holy people? Jesus emphatically provides this assurance, "Truly, truly, I say to you, he who hears my word, and believes Him who sent Me, has eternal life, and does not come into judgment but has passed out of death into life" (John 5:24). Jesus' apostle John also writes, "And the testimony is this, that God has given us eternal life, and this life is in His Son. He who has the Son of God has the life; he who does not have the Son of God does not have the life" (1 John 5:11-12). Despite this, many Believers are insecure and have doubts and uncertainty.

For new Believers, the basis of their insecurity may be rooted in their understanding of faith (see the series on faith starting with What is the concept of "faith" in the Old Testament?).

It is not uncommon to wonder if it is really that simple: just have faith in Jesus Christ. It seemingly defies logic, because people don't forgive others easily much less sacrifice their only son for an enemy.

For those who have been Believers for awhile, their insecurity may be rooted in their achievement. To be "Christ like" defines a standard (i.e. behavior or character) for self appraisal or comparison, and sometimes it mistakenly becomes the basis of a saving faith.

This may produce such questions as: what does God expect from me? What good deeds must I do to be saved? Did I do enough?

Thus Jesus' assurance is only good for those who have a genuine faith in Him. Genuine Christians have the confidence of knowing:

Their sins have been forgiven (see A Word Study of the Greek Terms Hilastērion and Hilasmos - Expiation verses Propitiation).

Their relationship with God has been restored (Rom 5:10-11) (see Does God reconcile Himself or is it man who is reconciled?).

They are of God's people with a responsibility (Matt 28:19; Mark 16:15; Luke 9:59-60) and a beneficiary of eternal life (1 John 5:12).

With this understanding, assurance is predicated on one's belief in Jesus as a historical figure and trust in His work of atonement (see What does "It is finished" mean? A word study of John 19:30). Since it is Jesus who provides the assurance, it is independent of how one emotionally feels.

Eternal security provides the basis for one's confidence in salvation.

It is a genuine faith alone that saves, and a genuine faith alone that assures (John 3:16-21). So there is no reliable outward sign or behavior that indicates whether one has salvation or not (1 John 2:18-19); it all comes down to whether you believe the gospel is in fact true and trust it.

In many ways a trusting faith comes down to how well one understands the facts and provisions of the gospel. The question of assurance is a consequence of doubt, and faith, or lack of, is a consequence of how that doubt is handled. The Bible provides many examples of how human beings deal with doubt, some constructively and others not.

There were those who did not have faith, because they doubted that Jesus was the Messiah; moreover, their doubt arose from the denial that Jesus was the Messiah.

The Bible records many examples of the Jews' refusal to accept the truth and reality of Jesus. For example, rather than recognizing Jesus' divine ability of healing (Matt 8:16-17) and fulfillment of Messianic prophecy (Isa 53:4), Jewish religious authorities attribute it to an evil spirit, "He casts out demons by the ruler of demons" (Mark 3:22); this contrived explanation had no basis in the Old Testament (Tanakh).

There were those who did not have faith, because they doubted that Jesus was God; Jesus the Savior meant nothing to them. These people only sought personal glory and wealth.

The Bible speaks of false prophets and teachers who secretly introduce destructive heresies, including the denial that Jesus was the Messiah, in greedy exploitation (2 Pet 2:1-3) or prestige (2 Cor 11:1-4, 13-15; 2 Thess 2:3-4; 1 John 2:18-22).

Simon the magician can be seen as an example of this (Acts 8:9-24).

Simon thought highly of himself and claimed to be someone great (Acts 8:9-11).

Simon "believed" the gospel, was baptized and observed amazing miracles (Acts 8:13).

Simon did not desire the Holy Spirit for himself; instead, he sought the authority of dispensing the Holy Spirit (Acts 8:14-19).

Simon did not understand the gospel and was never a genuine Believer. Simon's belief in the gospel can be seen as analogous to a demon's belief (James 2:14) which was an intellectual assent but not an understanding (1 Pet 1:10-12) or trusting belief in the gospel.

There were those who did not have faith, because they doubted the gospel. They saw Christianity as a lifestyle and thought they had faith, because they attended church.

Because the congregation of those who believed were of one heart and soul, and not one of them claimed that anything belonging to him was his own (Acts 4:32), Ananias and Sapphira's decision to withhold some of the proceeds of their land sale indicted that they were not Believers (Acts 5:1-2).

They apparently did not believe in the gospel expounded by the apostles Peter and John (Acts 4:33), and Peter's question of "putting the Spirit of the Lord to test" demonstrated the discernment of the Holy Spirit. Ananias and Sapphira, in their conspiracy to withhold money, did not believe that God was present and would know of their deceit.

There were those who did not have faith, because they had doubts that Jesus was the Messiah; however, they recognized that Jesus was of God and wanted to learn more.

Nicodemus (John 3:2), made the effort to rationally understand the truth of salvation that Jesus preached about (John 3:4). However, Jesus chides the teacher of the Law (John 3:10); Nicodemus should have been familiar with the principles of salvation written in the Old Testament (Ezek 36:25-28).

Jesus teaches the nature of faith to Nicodemus with an illustration of the bronze serpent (John 3:14-16; Num 21:4-9):

The nation of Israel was disobedient and spoke against God with their complaints of physical salvation from Egypt (Num 21:4-5).

The nation was being punished for their sin with lethal snakes (Num 21:6).

The nation recognized that they sinned and were helpless of saving themselves (Num 21:7).

The nation had to trust God's word and be obedient by looking at the bronze serpent for physical salvation (Num 21:8-9).

Nicodemus learned that faith, the belief and trust in something true, recognized the reality of man's condition and God's word, and that the object of a trusting faith was on God. This was in contrast to Jewish teaching, which required obedience to the Law as a condition for salvation and blessing. And it appeared later that Nicodemus believed that Jesus was the Messiah (John 19:38-39).

There were those who had faith in Jesus but had a variety of doubts, and yet were still obedient to Him.

In some ways like Nicodemus, the disciples had doubts because of their incomplete understanding of the Messiah and His function (Matt 28:16-17; Mark 16:14; Luke 24:36-43). However, they knew Jesus was the Messiah (Matt 16:13-20; John 1:41, 45, 49), and when they became apostles, they received supernatural help that enabled them to fully understand everything about the Messiah and the gospel (Luke 24:44-49; Acts 1:8).

A trusting faith has the character of obedience.

The Bible does not provide an example of a genuine Believer who had doubts and then explicitly rejects Jesus as the Messiah and denies His deity.

However Hebrews 6:4-8 is a passage that has been contested as an example of a genuine Believer who "lost his faith." There are several phrases that indicate that a genuine Believer is being discussed:

Given that Believers are "born again" (John 3:3-5), are "new creatures" (2 Cor 5:17-19) and given a pledge of their inheritance with a view of their redemption as God's own people, with the sealing of the Holy Spirit (2 Cor 1:21-22; Eph 1:13-14; 4:30), it does not seem possible that a genuine Believer can fall away (Heb 6:6).

Despite a genuine Believer's struggle with sin until death, it seems clear that one cannot deceive God if there were any future intent of apostasy (Heb 4:12-16).

In addressing immature Believers (Heb 5:11-14; 6:1) the writer of Hebrews appears to be answering an unspoken question of whether a genuine Believer who deliberately defects and rejects Christ can return as a genuine Believer. The response seems emphatically negative on this possibility as the defector would have such a hard heart that repentance would be impossible and figuratively seen as a second crucifixion of Jesus (Heb 6:6). The implication is that the person who fell away was never a genuine Believer in the first place very much akin to Ananias and Sapphira, who outwardly exhibited the behavior of genuine Believers (Acts 5:1-2), but were not (Acts 4:32-34).

The reference to agriculture is reminiscent of Jesus' parables and parallels the impossibility of a genuine Believer becoming an apostate (Heb 6:7-8).

In the Parable of the Sower (Matt 13:1-9, 18-23; Mark 4:1-9, 14-20; Luke 8:4-8, 11-15), the seed sown, symbolic of the gospel, never once yielded thorns or thistles. However in the Parable of the Tares (Matt 13:24-30; 36-43), the enemy sowed seeds that yielded tares (thorns). While both parables are in reference to the kingdom of God, the Parable of the Tares is clear as to what happens to the thorns at harvest.

Of the examples seen above, there are two examples of constructive ways of dealing with doubt.

Nicodemus exemplified a non-Believer who pursued the truth by following up his questions, and he ultimately realized that Jesus was indeed the Messiah and believed in Him.

The disciples exemplified Believers who, despite their doubts, were faithful and obedient to Jesus. For their faith, they received the Holy Spirit who would help them understand the gospel and the truth of Jesus. And this indwelling of the Holy Spirit occurs for all who have a genuine faith in Jesus Christ.

Jesus intended His assurance as a statement of historical fact (John 5:24; 1 John 5:11-12). Those who genuinely have faith in Jesus Christ will be forgiven of their sins and will have eternal life.