"...the sacrifice of Christ is no longer there for one "who has spurned the Son of God, and profaned the blood of the covenant by which he was sanctified"; such a one can "throw away [one's] confidence" and "shrink back" and be "destroyed" (Hebrews 10:28-39). The only thing such a sinner looks forward to is judgment, for "the Lord will judge his people" (cf. Romans 2:5-10). We are to keep faith and endure to the end to be saved, "so that you may do the will of God and receive what is promised" (cf. Matthew 24:13; 2 Peter 1:10f)."
The text from Matthew is descriptive, not prescriptive, in nature. The text from 2 Peter simply gives us a picture of what takes place in sanctification and does not concern the instance of justification itself.
"...the final step into heaven would require us to be perfectly purified and made completely holy through Christ’s grace, since the church in heaven, where "nothing unclean can enter" contains holy and perfected people (cf. Matthew 5:48; Hebrews 12:14, 23; 1 Thess 5:23; Eph 5:26f; Rev 21:27). So we DO "need to be purified" according to Scripture (cf. Mal 3:2-3; 1 Peter 1:6-9; 1 Cor 3:12-15; Hebrews 12:29), and Christ's one sacrifice is the application of that final purification and sanctification necessary for heaven -- which Catholics call "purgatory."
Certainly, we must persevere in faith and nothing unclean can enter heaven. The point of contention is whether good works are meritorious. If a person is interested in further discussion on whether Purgatory is an integral part of being purified in order to enter the kingdom of God, then he or she can view articles here and here.
"There is no evidence in Scripture of the infamous mantra “To be absent from the body is to be present with the Lord” (some say it is implied in 2 Corinthians 5:6-8 which actually reads: "we would rather be away from the body and at home with the Lord" -- RSV). There is often desire to be away from the body and be with Christ, but what believer wouldn’t desire this?"
In order to respond to the above objection, the surrounding context of 2 Corinthians 5:6-8 has been presented:
"For we know that if the earthly tent which is our house is torn down, we have a building from God, a house not made with hands, eternal in the heavens. For indeed in this house we groan, longing to be clothed with our dwelling from heaven, inasmuch as we, having put it on, will not be found naked. For indeed while we are in this tent, we groan, being burdened, because we do not want to be unclothed but to be clothed, so that what is mortal will be swallowed up by life. Now He who prepared us for this very purpose is God, who gave to us the Spirit as a pledge. Therefore, being always of good courage, and knowing that while we are at home in the body we are absent from the Lord—for we walk by faith, not by sight—we are of good courage, I say, and prefer rather to be absent from the body and to be at home with the Lord. Therefore we also have as our ambition, whether at home or absent, to be pleasing to Him." (2 Corinthians 5:1-9, emphasis added)
The Apostle Paul clearly sets up a twofold division between absence and presence. So it is erroneous to assert that the "famous mantra" has "no evidence" in Scripture. Ron Rhodes, in his work titled Reasoning from the Scriptures with Catholics, notes:
There are a number of passages in Scripture that mention the intermediate state and nowhere is the idea of purgatory even hinted at (John 14:1-4; Revelation 7:14-17; 20:11-15). All these texts point to the souls of believers going directly to be with God in heaven after death. Nowhere is a temporary abode that exists to purify our souls of venial sin spoken of. The repentant thief on the cross was promised eternal bliss that same day by Jesus Christ Himself (Luke 23:39-43).
The view of purgatory that has been a tradition of Roman Catholicism for centuries is that it is a place of intense suffering to satisfy divine justice. This experience is anything but pleasant. In Catholic theology, purgatory exists for people to make atonement for the remaining guilt of venial sin committed during their earthly lives. Purgatory has been described as a sin purifying fire. Therefore, Roman Catholic apologists who describe purgatory in terms of peace, bliss, and excitement are not at all representing historic belief.
Primitive writers such as Clement of Rome and Polycarp refer to Christians as being in heaven without any mention of purgatory. One Eastern Orthodox blogger makes the following point regarding the consensus of belief in purgatory in the early church:
"...if the doctrine of Purgatory was well-established Jewish belief that was carried into Christianity since Apostolic times, why was the doctrine doubtful even in the fifth century? Augustine himself vacillated on the issue. In the Handbook of Faith, Hope, and Love his comment on the doctrine’s doubtfulness reveal that it was surely not universally accepted in his own time: “It is a matter that may be inquired into, and either ascertained or left doubtful, whether some believers shall pass through a kind of purgatorial fire” (Chap 69). In City of God he speaks to the same effect: “But if it be said that in the interval of time between the death of this body and that last day of judgment and retribution which shall follow the resurrection, the bodies of the dead shall be exposed to a fire of such a nature that it shall not affect those who have not in this life indulged in such pleasures and pursuits as shall be consumed like wood, hay, stubble…this I do not contradict, because possibly it is true” (Book 21, Chap 26)."