Your assumption that only jews were allowed lend money is quite wrong. I will focus mainly to Italy but the following is actually pretty general (even if the attitude in protestant countries might be different - I do not have any specific knowledge about this eventual difference).

 

A good number of italian bankers were good christians or at least they tried to be. Lending money was generally percieved as a sin and therefore something they needed to atone for, both for personal belief and to solidify their often newly acquired status.

It is not a surprise therefore that the leading bankers were also great patrons of the arts, builders of churches and so on.

It does not mean that atonement was to be obtained easily or cheaply. One prominent example was Rinaldo degli Scrovegni who died around 1288 and had become extremely rich thanks to his money lending; he also gained infamy for ruining a large number of people in the city of Padua (the crucial point being that he was neither very pious nor very concerned with gaining approval). Dante would later put him in hell, showing a widespread disdain for such excesses^1. Rinaldo's son, Enrico degli Scrovegni feeling the need to reabilitate his family name - while he did not give up his father's business - spent a large amount of money to build a chapel and had it frescoed by Giotto (1318) - at the time already a prominent figure in italian arts. He even had himself painted among the aspiring to salvation in the universal judgement, in the act of gifting the chapel to the Virgin Mary.

Even more prominent among the italian bankers were the Bardi and the Peruzzi of Florence - who notably went bankrupt when King Edward III (of England) failed to pay them back the sum of 1,500,000 gold florins. Both these families were active patrons and you can find a large amount of churches and buildings which benefited from their donations; for example you can find both a Bardi and a Peruzzi chapels in Santa Croce in Florence (again both frescoed by Giotto around 1320-25). Still in Florence - in S. Maria Novella this time - another remarkable chapel was painted in the late XV century under patronage of the banker Filippo Strozzi the old .

 

As an aside, Beatrice the woman who served as a guide for Dante's voyage through Paradise is generally believed to have been the daughter of a Folco Portinari; whose business was money lending. This did not prevent his daughter to act as intermediary between man and God.

 

So, I believe that to be evidence that, while in Italy at least lending money was seen as a questionable activity, it was not forbidden on a general basis. A large number of family reached their status through this business - once they were rich enough it was common practice to spend part of their money to show their devotion.

 

As for the other side of your question. The situation is much more complex, since the treatment of jews, their rights, both personal and economical changed within time and space.

It is true though that, at certain times Jews were forbidden from purchasing land or buildings - or at least forbidden from purchasing land or buildings previously belonging to christians. In these instances it was possible for them to resort to money lending as the main form of investment available.

This is not generally true though; not for all Italy and ceratinly not over the entirety of the Middle Ages.

 

Furthermore it is not true that jews were generally allowed to practice money lending more than christians. Often, where restrictions were imposed over the business of Jews, these restrictions included the practice uf usury. It is impossible to give even a brief overview of the history of such legislation in Italy. I will limit myself to the city of Ferrara.

 

The presence of jews in Ferrara is documented at first through a series of business papers dating to the XIII century; they include purchasing of land which appears therefore not forbidden at the time.

In the early XIV century we have records of jews being sentenced to pay fees in order to keep their business within the city, under pressure by the Inquisition.

Things changed significantly during the next century when the ruling house of Este successfully argued that it was their prerogative to give license to practice money lending to jews, rather than the church's.

In 1448 an ordinance was issued forbidding preaches specifically targeted against jews.

In the 1490s Duke Ercole I d'Este welcomed a good number of Spanish Jews (and their business) to the city. They had the right to practice medicine, to purchase land and to bring their goods with them without paying any tax; but they could not obtain immediatly the right to practice money lending - which was more likely reserved for the more trusted jews already living in the city.

The status of the jews remained overall good in the city, even in the beginning of the XVI century when they were forced to wear a yellow hat under a decree of the new Duke Ercole I.

Their good status led to an increased immigration - from Portugal, Naples and Bohemia during the XVI century under Duke Ercole II - and increased attention from the Inquisition (the Congregazione della sacra romana e universale Inquisizione had been created in 1542 and was guided by Gian Pietro Carafa). Meanwhile the Este power was vaning slowly and the last Duke Alfonso II whose power was to revert entirely to the church in the early XVII century had to cave in to the pressure of the new Pope. Gian Pietro Carafa had indeed upgraded from President of the Inquisition to Pope under the name Paul IV.

One of his first acts was to address the matter of the jews with the bull Cum nimis absurdum (Since it is utterly absurd) in 1555. The text quite clearly shows a different attitude towards the jews:

Since it is utterly absurd and despicable that the jews, who only for their own sin are submitted to eternal slavery, could, with the excuse [of christian charity], [...] demand to rule instead of being ruled.

The bull set a number of rules: jews were to live in ghetti far from churches, to have only a sinagogue in each city, to wear some azure marking - usually on their head. But they also could not loan money to christians, neither they could do ordinary business with the exception of trading in used garments and cereal wares.

Now, this piece of legislation was not to last. And many of its points were emended by the new Pope Pius IV only to be reinstated by Pius V and then again modified over and over. It must also be noted that not every local administration was ready to apply the church's instructions. For example in many cities under the church sovereignty, they were forbidden from acquiring land or buildings form christians. Later they would be allowed to loan money but not to take buildings or land as collateral from christians - or in certain cases only after a significant delay in payment.

We have left the middle ages already so I think I should stop here. This shoud nonetheless suffice to show that the jews were not always forbidden to own land or to practice "regular" businesses and that they were at times forbidden from lending money. The entire set of rules was extremely complex and varied deeply form place to place; also these rules changed often within years.

 

1 - He earned himself this flattering description:

 

And one, who with an azure sow and gravid

Emblazoned had his little pouch of white,

Said unto me: "What dost thou in this moat?

 

Now get thee gone; and since thou'rt still alive,

Know that a neighbour of mine, Vitaliano,

Will have his seat here on my left-hand side.

 

A Paduan am I with these Florentines;

Full many a time they thunder in mine ears,

Exclaiming, 'Come the sovereign cavalier,

 

He who shall bring the satchel with three goats;'"

Then twisted he his mouth, and forth he thrust

His tongue, like to an ox that licks its nose.