Two good figures to look into are:

Bartolomé de las Casas who wrote A Short Account of the Destruction of the Indies. He was deeply effected by his witnessing of the Spanish Conquest, eventually become the official "Protector of the Indians."

Next is Juan Ginés de Sepúlveda, De las Casas' rival in the Valladolid Debate, and a major advocate for the brutality and psuedo-enslavement of the Indians during the Conquest.

Next look at all these major native uprisings against the Spanish:

Tepehuán Revolt, Acaxee Rebellion, Pueblo Revolt.

And for the Mission System:

Uprising at Mission San Gabriel 1771

A revolt at Mission San Diego 1775

Toypurina's revolt against Mission San Gabriel 1785

Another example is the poisoning of Father Jose Pedro Panto by his cook Nazario in 1815. Nazario slipped poison into Panto's soup because the priest had ordered him flogged over 100 times. A brutal flogging caused another uprising at the La Purísima Mission in 1824.

I think that a decent number of examples to show your teacher that life for the Indians in New Spain was the exact opposite of a blessing.

Just like many other arguments about history, with sufficient compartmentalization and selective interpretation, your teacher just may have a point.

Spanish attitude on the natives of the New World evolved quite a bit. Columbus' journeys were chartered with specific instruction that he "endeavor to win over the natives," and "treat them well, lovingly, and abstain from causing them injury." In his first letter back to the Monarchs, he wrote, ".... so that they would be won over and, moreoever, become Christians inclined toward love ..."

In his later expedition and rule of an outpost, he forbade baptism of natives except with his personal permission, in order to maintain an adequate supply of slaves. Other conquistadors were also cruel in their treatment of natives, I won't get into that here, even if they attempt to justify it on account of a civilizing mission.

Las Casas wrote a scathing report on the abuses and championed a different more humane system. To a large part, he was able to get royal support even if this took decades. By that point, Spanish exploration were mostly in central and south Americas.

As they expanded north the attitudes had changed greatly. To quote a previous post by /u/anthropology_nerd

After the excesses of cruelty seen in the initial years of contact, the 1573 Comprehensive Royal Orders for New Discoveries, placed missionaries at the forefront of exploration and pacification of new lands. Instead of valiant conquistadores rampaging into new territory, the Orders prohibited the entry of unlicensed entradas into new lands, and prohibited violence against Indians, under threat of fine or death. Entradas were to be led by conquistadores of the spirit, most often by the Franciscans along the northern frontier of the Empire, though Jesuits briefly established missions in Florida, as well as longer-lived missions among the Pima in southern Arizona.

In particular, Franciscan missionaries dominated the northern frontiers of the Spanish empire in the Americas, from California to Florida. They established missions, meaning frontier parishes, where the friars live and encourage native Americans to settle in the vicinity. They would be instructed in proper Christianity and the "Spanish way", work for the benefit of the community, and in exchange they would be given access to goods, instructions in farming, and access to livestock. Of course, all these are merely worldly benefits secondary to the utmost important salvation of one's soul in Christ!

Of course, as mentioned elsewhere, not all was peaceful and mutually beneficial. Soldiers often accompanied preachers. There were often conflict. There were outright rebellions. But as a matter of policy, the stated strategic goal of Spanish activities was to gain the allegiance of native Americans and to convert them to Catholicism. However, to focus on only this formal policy aspect is unfair.

I shall allow my colleagues such as /u/Dubstripsquads fill you in on "dirty Protestant" attitudes on native Americans.

Well both the Protestants and Catholics, from the onset, viewed Native Americans and their religions with contempt. To the Europeans, the local religions were in fact irreligious or even described as being a form of devil worship. Thus even in the beginning there is a negative perception of Native Peoples and their lifestyle, and a fair bit of emphasis was put on converting these 'heathens' to Christianity in the form of Catholicism/Protestantism.

In terms of the missions, they had a few additional effects (mainly detrimental) apart from just being a way of converting the local population. In a fair few instances the local populations were forced into these missions against their will, and often the missions forbade those inside from returning to their tribes just in case they get re-converted. I know that the Illinois native population decline can be attributed in part to the introduction of monogamy to the newly converted Catholic natives, thus considerably bringing down the birthrate of a once polygamous community.

If your theology teacher believes that Catholicism was a 'blessing' to the American people, then he obviously hasn't read some of the accounts of those who did convert. A story from the Mesquakie people stands out for me: A converted Mesquakie Catholic passes away after living a hard life, and in the afterlife he faces the conundrum of being refused access from both the Indian hereafter for being a convert and from Christian heaven for being a native. In essence, just being a convert didn't really make your life much better since you were still a Native American, and thus were treated as inferior by the Europeans. By converting you also distance yourself from your own roots, people and ancestors.

I can't give too much more detail since I'm not majoring in this area, but I think it is quite despicable what your teacher is saying as he replacing any real historical evaluation with his own personal beliefs and views.