Give an exmple of corruption in the church?

Speaking for the 12th century Church in Anglo-Norman England, the only corrupt practices I have discovered were forcedupon Church officials by the king. These refer to land titles and legal powers granted under earlier kings; where such written records could not be produced, kings such as Henry II and John were in the habit of confiscating lands from the church or removing legal rights.

In one particular instance, a monastery was consumed by a huge fire which destroyed all its written legal documents; the buildings were repaired, but in order to escape having all its lands and rights confiscated by the king the Abbot was forced to forgeall the legal texts (even going so far as to forge the ancient seals attached to those documents). The scribes were hard pressed to remember the detailed and technically complex contents of documents which they could remember only vaguely.

In many cases the Church held lands and rights without ever having a document proving it; in such cases it was common for legal documents to be forged and back-dated. The false nature of such texts is obvious to modern researchers, since they do not use the writing style of the period they are supposed to date from and seals are often of the wrong period.

Although such forgeries could be termed "corrupt", the reasons behind them are entirely genuine and honest. They are symptomatic of the uneasy and volatile relationships between Church and king.

Second Answer

It is a well-documented fact that the medieval Roman Church tortured and killed an estimated 150 million Christians and Jews because they refused to convert (Jews) or refused to follow the doctrine of the Church because it deviated from holy scripture (Christians). The Church banned bibles, taxed the locals, demanded payment for forgiveness of sins, confiscated land, money and other personal property on a whim. If this does not sound like corruption and pure evilness, I don't know what does.