If that were so, shouldn't the above assertion be itself someplace in the Holy Scripture?
Shouldn't, further the assertion that the Church is our sole guide (Mt. 18:17) be not in the scripture?
Expected straw man argument. Your own religion teaches that the Holy Scriptures are divinely inspired and as the Word of God they are given to Christians for teaching, rebuking, correcting and training in righteousness, so that the servant of God may be thoroughly equipped for every good work. (II Timothy 3:15-17)
Therefore, the argument should be about what Scripture teaches about this so-called Purgatory, NOT whether or not Scripture is relevant. So, based upon that, the question remains "What does Scripture teach about Purgatory?". The answer is NOT ANYTHING. The verses quoted in an attempt to prove the concept by Scripture is obviously lame. Every one given is never in support of such a place. In fact, Scripture very clearly teaches that there is never any need for such a place.
We know from many Scriptures that ALL have sinned, ALL are in need of a Savior. Proverbs 20:9 says, "Who can say, 'I have kept my heart pure; I am clean and without sin'?" Romans 3:23 says, "For all have sinned and fall short of the glory of God."
We also know that without the shedding of blood there is NO remission of sins. Hebrews 9:22-23 says, "In fact, the law requires that nearly everything be cleansed with blood, and without the shedding of blood there is no forgiveness." Leviticus 17:11 says, "For the life of the flesh is in the blood, and I have given it to you upon the altar to make atonement for your souls; for it is the blood that makes atonement for the soul."
And lastly, we know that through the blood of Jesus Christ, we are cleansed from all sin. Hebrews 9:22-28 is very clear, "In fact, the law requires that nearly everything be cleansed with blood, and without the shedding of blood there is no forgiveness. It was necessary, then, for the copies of the heavenly things to be purified with these sacrifices, but the heavenly things themselves with better sacrifices than these. For Christ did not enter a sanctuary made with human hands that was only a copy of the true one; he entered heaven itself, now to appear for us in God’s presence. Nor did he enter heaven to offer himself again and again, the way the high priest enters the Most Holy Place every year with blood that is not his own. Otherwise Christ would have had to suffer many times since the creation of the world. But he has appeared once for all at the culmination of the ages to do away with sin by the sacrifice of himself. Just as people are destined to die once, and after that to face judgment, so Christ was sacrificed once to take away the sins of many; and he will appear a second time, not to bear sin, but to bring salvation to those who are waiting for him.
We know that there is no other "place of cleansing" but Jesus Christ and that we are made holy, sanctified, justified, made righteous by the grace of God through faith in Jesus Christ. He gave his life in place of ours, and by his sacrifice - his once for all sacrifice - we may enter Heaven when we die. We have been cleansed of ALL sin, there is no need for an intermediate place for further cleansing. To teach this (Purgatory) is to ignore Scripture and the entire purpose for the cross. That is why we can count on the Holy Scriptures for the Holy Scriptures are able to make you wise for salvation through faith in Christ Jesus. (II Timothy 3:15)