There are New Testament passages that emphasize the powerful grace of God that keeps Christians in the faith, and there are New Testament passages that emphasize Christians' responsibility to persevere in faith. We'll call these two groups of passages: Data Set One and Data Set Two, respectively.
Data Set One (Divine Grace that Keeps Christians in the Faith)
According to John 6:37-44; 10:27-30, Jesus will never lose any of his people; no one can snatch them out of his hand.
According to Ephesians 1:13-14; 4:30; and 2 Corinthians 1:22; 5:5, the Holy Spirit seals believers, guaranteeing our future possession in advance.
Paul speaks of the powerful preserving grace of God in passages such as Romans 8:28-39; Philippians 1:6; and 2 Timothy 1:12. Peter speaks similarly of God's power that guards us until the end (1 Peter 1:5).
Passages about the New Birth (e.g., John 3) and New Covenant (e.g., 2 Corinthians 3) speak of a radical inward transformation and a new power for holiness. The old is gone; the new has come.
Data Set Two (Christians' Responsibility to Persevere in Faith)
The warning passages in Hebrews, especially 6:4-8 and 10:26-38 indicate that true believers can renounce their faith. There is a similar teaching at John 15:1-6; and 2 Peter 2:20-22.
There are passages that confront Christians with a condition: in order to receive the promises of grace, they must persevere in faith until the end: Matthew 10:22; John 8:31; Romans 11:20-22; Colossians 1:22-23; Hebrews 3:6, 14.
Jude 1:21 suggests that the believer has a responsibility to remain inside the sphere of God's love.
There are many examples of apostasy in Scripture; for example, Demas, who was formerly one of Paul's co-laborers (2 Timothy 4:10).
There are three basic ways of integrating the data above:
View One (This view emphasizes Data Set One: Divine Grace)
View One states that once an individual has experienced the New Birth and has trusted in Christ for the forgiveness of sin, that individual can never revert to an unconverted state.
For View One, 1 John 2:19 is a particularly important verse, especially the line: "if they had been of us, they would have continued with us." According to this view, this verse indicates that apostates were never true Christians to begin with. Similar to this is a particular interpretation of Hebrews 3:14: perseverance to the end is what demonstrates that we had originally come to share in Christ. These two verses are then sometimes linked to the parable of the soils (Mark 4) -- even though some "believers" spring to life and joy, they fall away in response to persecution, and thus bear no fruit.
Some who hold to View One say that the warnings of Hebrews 6:4-8 and 10:26-38 are merely hypothetical; others say that the people described in these verses experienced a significant amount of grace, but were never true believers.
This view is usually referred to as Calvinistic (after John Calvin, 1509–1564).
View Two (This view emphasizes Data Set Two: Christians' Responsibility)
View Two agrees that divine grace preserves the Christian, but argues that such grace is forfeited if the Christian renounces their faith in the God of grace.
View Two points out that the responsibility of faith is mentioned within some of the promises of grace (e.g., "everyone who believes" in John 6:40; "through faith" in 1 Peter 1:5).
This view is sometimes referred to as Arminian (after Jacobus Arminius, 1560–1609).
View Three (This view attempts to hold the two in Balance, saying they are Compatible, and that there is an element of Mystery involved)
This view wants to avoid what the two previous views do when they are at their worst: they use their preferred passages to reduce the force of the alternate data set. On the basis of their theological system, they use fancy interpretive maneuvers to skirt the teaching of those alternate biblical passages.
This view notes things that View One and View Two hold in common. For example, both views hold that the ultimate ground of a Christian's confidence is not the response of human faith, but rather the object of that faith -- the grace of God manifested in Christ's work on the cross. Both views also recognize that the biblical warnings are one of the means by which God keeps his people in the faith.
This view notes that throughout Scripture, God's sovereign grace and human responsibility work hand in hand . For example, Philippians 2:12-13 calls upon the believer to work out their salvation (with trembling) because it is God who works in them.
This view also notes that there are things we mere mortals simply cannot understand. For example, God exists outside of time, while we are stuck inside of time -- so how do God and humans relate to each other with respect to time? We are unable to say for certain.
This view emphasizes the functions of the different data sets. The function of Data Set One (Divine Grace) is not to encourage laziness, but confidence. The function of Data Set Two (Human Responsibility) is not to encourage anxiety, but faith and faithfulness. Both sides of the coin are necessary.
In Trinity Fellowship, as long as one is making a sincere effort to honor Scripture, we don't require anyone to hold to a particular one of these views in order to be a member. Our statement of faith does not specify that we as a church hold to one of these views.
There are, however, two extremes that we want to avoid:
The first is an extreme position that suggests that any small amount of faith in Christ, even if not evidenced by good works, or even if later renounced, is still enough to bring one to Heaven.
The second is the opposite constantly-anxious-and-never-confident-in-Christ view that worries "I could lose my salvation at any moment." This extreme might suggest, for example, that if I die in a car accident because I was disobeying God by breaking the speed limit, that my momentary lead foot on the accelerator will send me to Hell.
Finally, note how the term, "confidence," in Hebrews 10:19–39 integrates divine grace and human responsibility. We are to be confident in the grace of Christ, and, as an expression of that confidence, to persevere in faith.