Christian influence in the Spanish gastronomy is without doubt an important one, but it is most certainly not the only one. Nowadays most of Spain is Catholic, but back in the day, many centuries ago, the religion did not have quite the monopoly that it does today. The Jews had lived in Spain for centuries but in the year 638 they began to be prosecuted as king Chintila decided he wanted to convert them by force through and oath. Lucky for them a few years later (710) the Muslim invasion of Spain began and occupied a large part of the peninsula, and in times of Caliphate, Jews were accepted, they no longer needed to run, hide or convert.
There were vast areas where territory was divided by religion, and others, especially larger cities, where they all lived together. This cultural exchange meant a change in the culinary customs of all three religions, and we can safely say that Spanish gastronomy wouldn't be the same without one of them.
Christians were direct heirs of the Visigoths, who in turn were heirs of the Romans, and this is also true of their gastronomy. From chronicles of the time we know that more or less until the 12th century Christians typically ate once, at most twice a day, and it was recommended to eat and drink with restraint.
The amazing Spanish ham process was developed by Christians, as the meat was forbidden for both, Jews and Muslims. When it came to pork, Christians took advantage of the whole animal, nothing would be wasted and although some people may wrinkle their noses, for many years all those parts of the pig that were frowned upon by the rich, fed the poor. Christian influence in the Spanish gastronomy is specially notorious when it comes to pork. Be sure to try the best ham that the country has to offer which you will find in the markets and the bars of Spain.
Religion certainly played an important part when it comes to gastronomy, particularly with the creation of specific dishes for certain religious events and occasions. For example, there were a number of dishes especially prepared for lent (without any kind of meat save for fish) and Sundays, which gave way to a vast variety of fish and shellfish dishes, legume stews without meat and all manner of desserts made without the use of any animal fat.
There are also many traditions with regards to the food consumed in Easter. Garlic soup is normally consumed during this time whilse cod is yet another main ingredient in many Spanish tables, croquetas are abundant and fritters make a special appearance. Gastronomically speaking, Spain is an interesting country and it is at its greater during the Easter period.
The Christian influence in the Spanish gastronomy is also important when it comes to desserts and sweetmeats. It is said that Marzipan (March bread) was created in Toledo in the 11th century, invented by the nuns of the Convent San Clemente in times of famine. There was no wheat in their storerooms, but they did have plenty of sugar and almonds, and so using a bit of their intiative, they invented marzipan. There's a contending hypothesis that it was invented in Sicily as well.
But nuns invented many other desserts and cakes and many of those convents still make and sell the same traditional desserts, such as "suspiro de monja" (nun's sight), torrijas, wine rolls and many other tasty treats. In the past wealthy families would commission desserts, buns, sweets and cakes from nuns who would thus increase their income. There are some desserts that even today can only be found in convents.
As of late, when Catholicism is undergoind a bit of fall in popularity in the country, and many of those who are Catholic no longer stick to the rules so strictly, much of the Lent and Easter gastronomy is being lost. An excellent reason for you to start learning how to cook some of these great Spanish dishes and protect them from gastronomic extinction. Despite this fact, Christian influence can be felt as much as Muslim and Jewish influence in the gastronomic culture of Spain.