http://www.scripturecatholic.com/salvation.html
Just a few scripture references from this site....
II. We are not Guaranteed Salvation; We Hope For Salvation
Heb. 7:27, 9:12,26;10:10; 1 Pet 3:18 - Jesus died once and redeemed us all, but we participate in the application of His redemption by the way in which we live.
Heb. 9:12 - Christ's sacrifice secured our redemption, but redemption is not the same thing as salvation. We participate in and hope for salvation. Our hope in salvation is a guarantee if we are faithful to Christ to the end. But if we lose hope and fail to persevere, we can lose our salvation. Thus, by our own choosing (not by God's doing), salvation is not a certainty. While many churches believe in the theology of "once saved, always saved," such a novel theory is not found in Scripture.
Rom. 5:2 - we rejoice in the "hope" (not the certainty) of sharing the glory of God. If salvation is assured after accepting Jesus as Savior, why would Paul hope?
Rom. 5:5 - this "hope" does not disappoint us, because God's love has been poured into our hearts through the Holy Spirit.
Rom. 8:24 - this "hope" of salvation that Paul writes about is unnecessary if salvation is guaranteed. If salvation is assured, then why hope?
Rom. 10:1 - Paul prays that the Jews "may be saved." Why pray if it's guaranteed? Further, why pray unless you can mediate?
Rom. 12:12 - rejoice in your "hope" (not your certainty), be patient in tribulation, and be constant in prayer.
2 Cor. 3:12 - since we have a "hope" (not a certainty), we are very bold.
Gal. 5:5 - for through the Spirit by faith we wait for the "hope" (not the certainty) of righteousness.
Eph. 1:18 - that you may know what is the "hope" to which He has called you, what are the riches of His glorious inheritance.
Eph. 4:4 - there is one body and one Spirit, just as you were called to the one "hope" (not the one certainty) that belongs to your call.
Phil. 3:11 - Paul shares Christ's sufferings so that "if possible" he may attain resurrection. Paul does not view his own resurrection as a certainty.
Phil. 1:20 - as it is my eager expectation and "hope" (not certainty) that I shall not be at all ashamed before Christ.
Col. 1:5 - Paul refers to the "hope" (not guarantee) that Christ laid up for us in heaven.
Col. 1:23 - provided that you continue in the faith, not shifting from the "hope" of the gospel which you heard.
Col. 1:27 - to them God chose to make known His mystery, which is Christ in you, the "hope" (not the certainty) of His glory.
1 Thess. 1:3 - remembering before our God your work of faith and labor of love and steadfastness of "hope" in Jesus Christ.
1 Thess. 2:19 - for what is our "hope" or joy or crown of boasting before our Lord Jesus at his coming? Is it not you?
1 Thess. 5:8 - we must put on the helmet of "hope" (not of certainty) of salvation.
2 Thess. 2:16 - the Lord Jesus and God our Father who loved us and gave us eternal comfort and good "hope" through grace.
1 Tim. 1:1 - Paul describes Christ Jesus as our "hope" (not our guarantee). We can reject Him and He will allow this.
1 Tim. 4:10 - Paul says we have our "hope" (not our assurance) on the living God. This is not because God is unfaithful, but because we can be unfaithful.
1 Tim. 5:5 - she who is a real widow, and is left all alone, has set her "hope" (not her assurance) on God. Our hope is a guarantee only if we persevere to the end.
2 Tim. 2:10 - Paul endures for the elect so that they "may also obtain salvation." This verse teaches us that even the "elect" have no guarantee of salvation.
Titus 1:2 - Paul says that he is in the "hope" (not the certainty) of eternal life. Paul knows that his hope is a guarantee if he perseveres, but his ability to choose sin over God makes his attainment of eternal life less than a certainty until it is actually achieved.
Titus 2:13 - awaiting our blessed "hope," the appearing of the glory of our great God and Savior Jesus Christ.
Titus 3:7 - Paul says we have been given the Spirit so we might become heirs in the "hope" (not the certainty) of eternal life.
Heb. 3:6 - we are Christ's house if we hold fast our confidence and pride in our "hope" (not our certainty).
Heb. 6:11 - we desire each one of you to show the same earnestness in realizing the full assurance of "hope" (not certainty) until the end.
Heb. 6:18 - we who have fled for refuge might have strong encouragement to seize the "hope" (not the certainty) that is set before us.
Heb. 6:19 - we have a "hope" that enters into the inner shrine behind the curtain, where Jesus has gone before us.
Heb. 7:19 - on the other hand, a better "hope" (not certainty) is introduced, through which we draw near to God.
Heb. 10:23 - let us hold fast the confession of our "hope" without wavering, for He who promised is faithful.
Heb. 11:1 - now faith is the assurance of things "hoped" for (not guaranteed), the conviction of things not seen (heaven).
James 1:12 - we must endure trial and withstand the test in order to receive the crown of life. It is not guaranteed.
1 Peter 1:3 - by His mercy we have been born anew to a living "hope" through the resurrection of Jesus Christ from the dead.
1 Peter 1:13 - set your "hope" (not assurance) fully upon the grace that is coming to you at the revelation of Jesus Christ.
1 Peter 1:21 - through Him you have confidence in God, who raised him from the dead so that your faith and "hope" are in God.
1 Peter 2:2 - like newborn babes, long for spiritual milk, that by it you may grow up to salvation.
1 Peter 3:15 - always be prepared to make a defense to anyone who calls you to account for the "hope" that is in you.
1 John 3:3 - and everyone who thus "hopes" in Him purifies himself as He is pure.
IV. Jesus' Teaching on Losing Salvation
Matt. 7:18 - Jesus says that sound trees bear good fruit. But there is no guarantee that a sound tree will stay sound. It could go rotten.
Matt. 7:21 - all those who say "Lord, Lord" on the last day will not be saved. They are judged by their evil deeds.
Matt. 12:30-32 - Jesus says that he who is not with Him is against him, therefore (the Greek for "therefore" is "dia toutos" which means "through this") blasphemy against the Spirit will not be forgiven. This means that failing to persevere in Jesus' grace to the end is the unforgivable sin against the Spirit. We must persevere in faith to the end of our lives.
Matt. 22:14 - Jesus says many are called but few are chosen. This man, who was destined to grace, was at God's banquet, but was cast out.
Luke 8:13 - Jesus teaches that some people receive the word with joy, but they have no root, believe for a while, and then fall away in temptation. They had the faith but they lost it.
Luke 12:42-46 - we can start out as a faithful and wise steward, then fall away and be assigned to a place with the unfaithful.
Luke 15:11-32 - we can be genuine sons of the Father, then leave home and die, then return and be described as "alive again."
John 6:70-71 - Jesus chose or elected twelve, yet one of them, Judas, fell. Not all those predestined to grace persevere to the end.
John 15:1-10 - we can be in Jesus (a branch on the vine), and then if we don't bear fruit, are cut off, wither up and die.
John 17:12 - we can be given to Jesus by the Father (predestined to grace) and yet not stay with Jesus, like Judas.
John 6:37 - those who continue to come to Jesus He won't cast out. But it's a continuous, ongoing action. We can leave Jesus and He will allow this because He respects our freewill.
John 6:39 - Jesus will not lose those the Father gives Him, but we can fall away, like Judas. God allows us not to persevere.
John 6:40 - everyone who sees the Son and believes means the person "continues" to believe. By continuing to believe, the person will persevere and will be raised up.
John 6:44 - Jesus says no one can come to me unless the Father "draws" him. This "drawing" is an ongoing process.
John 10:27-28 - when Jesus says, "no one shall snatch them out of my hands," He does not mean we can't leave His hands. We can choose to walk away from Him.
Rev. 3:4 - in Sardis, Jesus explained that many people received the white garment and soiled it with sin.
Rev. 3:5 - Jesus says whoever conquers will not be blotted out of the book of life (see Exodus 32:33). This means that we can be blotted out.
Rev. 3:11 - Jesus says to hold fast to what we have, so that no one may seize our crown. Jesus teaches us that we can have the crown and lose it.
Rev. 13:10; 14:12 - we are called from heaven for the endurance and faith of the saints, keeping the commandments and faith.
Rev. 21:7 - we must conquer in order to share in our heritage and become a true son of Jesus.
Rev. 22:19 - we can have a share in the tree of life in God's holy city and yet have that share taken away from us.