A few Bible verses that back up the Catholic teaching on purgatory:

"For if he were not expecting that those who had fallen would rise again, it would have been superfluous and
foolish to pray for the dead. But if he was looking to the splendid reward that is laid up for those who fall asleep in
godliness, it was a holy and pious thought. Therefore he made atonement for the dead, that they might be
delivered from their sin" (2 Macc. 12:44-45).

“For this is why the gospel was preached even to the dead, that though judged in the flesh like men, they might
live in the spirit like God. (1Pet.4:6)  
Why did the dead need preached to if they are in heaven or hell?  
They must have been elsewhere.

"Make friends quickly with your accuser, while you are going with him to court, lest your accuser hand you over to
the judge, and the judge to the guard, and you be put in prison; truly, I say to you, you will never get out till you
have paid the last penny" (Matt. 5:25-26).

"Each man’s work will become manifest; for the Day will disclose it, because it will be revealed with fire, and the
fire will test what sort of work each one has done. If the work which any man has built on the foundation survives,
he will receive a reward. If any man’s work is burned up, he will suffer loss, though he himself will be saved, but
only as through fire" (1 Cor. 3:13-15).
There is no suffering in Heaven and once you are in hell you are not
getting out.  This verse shows that there is a "place or process" where our souls will be cleansed so we
can enter heaven and obtain eternal salvation.

“Indeed, so terrifying was the sight that Moses said, "I tremble with fear."  But you have come to Mount Zion and
to the city of the living God, the heavenly Jerusalem, and to innumerable angels in festal gathering, and to the
assembly of the first-born who are enrolled in heaven, and to a judge who is God of all, and to the spirits of just
men made perfect,”  ( Heb 12:21-23).

"For Christ also died for sins once for all, the righteous for the unrighteous, that he might bring us to God, being
put to death in the flesh but made alive in the spirit; in which he went and preached to the spirits in prison, who
formerly did not obey ." (1 Peter 3:18-20).

"But nothing unclean shall enter it [heaven] . . ." (Rev. 21:27).   
Our souls need cleansed before they can
enter heaven if we are not perfect!

Something to consider:
What about Lazarus? He was already dead four days (John 11:17) when Jesus arrived
at his tomb.  Once your in heaven or hell you are not getting out. Where was his soul during those four days?
Protestant theology cannot properly explain this verse!


From the Catechism of the Catholic Church:

ARTICLE 12  - "I BELIEVE IN LIFE EVERLASTING"
III. The Final Purification, or Purgatory

1030
All who die in God's grace and friendship, but still imperfectly purified, are indeed assured of their eternal
salvation; but after death they undergo purification, so as to achieve the holiness necessary to enter the joy of
heaven.

1031
The Church gives the name Purgatory to this final purification of the elect, which is entirely different from the
punishment of the damned.  The Church formulated her doctrine of faith on Purgatory especially at the Councils of
Florence and Trent. The tradition of the Church, by reference to certain texts of Scripture, speaks of a cleansing
fire.

As for certain lesser faults, we must believe that, before the Final Judgment, there is a purifying fire. He who is
truth says that whoever utters blasphemy against the Holy Spirit will be pardoned neither in this age nor in the age
to come. From this sentence we understand that certain offenses can be forgiven in this age, but certain others in
the age to come.

1032
This teaching is also based on the practice of prayer for the dead, already mentioned in Sacred Scripture.
"Therefore [Judas Maccabeus] made atonement for the dead, that they might be delivered from their sin."  From
the beginning the Church has honored the memory of the dead and offered prayers in suffrage for them, above all
the Eucharistic sacrifice, so that, thus purified, they may attain the beatific vision of God. The Church also
commends almsgiving, indulgences, and works of penance undertaken on behalf of the dead.
Purgatory
The Catholic Church teaches that when we die, if we are not
perfect our souls will have to be made perfect before we can
enter heaven.  As the Bible says "nothing unclean shall enter
heaven".  This "process" or "place" is what the Catholic Church
calls purgatory.  In recent times some Catholics have been taught
that purgatory is an outdated teaching and is not Church doctrine
anymore.  This is simply not true and purgatory is now and has
always been a doctrine of the Church.

The teaching of Purgatory was rejected by the reformers in light
of their belief in the theology of
Sola Fide.  Some people wrongly
believe  that Purgatory was invented by the Catholic Church.  This
is simply not true and can easily be proven false.

The fact is that the Catholic theology behind purgatory can be
found in the scriptures and sacred tradition and does not
contradict the Bible as most non-catholics claim.