Not at all, people like Fray Junipero Serra employed more tame means, instead of going directly to Chichimec cities and towns in the region he would send riders forth to burn the crops and food reserves, latter as starvation settled in, he would share the food reserves of his Encomienda in exchange for the salvation of their souls and slav... err, indentured servitude in the Encomienda for undefined ammounts of time, which was totally not slavery, nope.

Okay, okay, so genocide-joking aside, Im going to take some liberties in your question, Im going to assume assume that by "conquistadors" you mean spaniard adventurers operating mainly in Mexico and South America and assume you meant Catholicism (not christianity, nitpick point yes, but it was important at the time so its important for explaining the period), that you're asking me about mainly Mexico, as I have little knowledge of the colonial period outside that region, and that we can extrapolate most of the systems used there to the rest of the Spanish colonial empire, and that you will not complain that I ramble a bit, Im no historian after all, only someone with an interest in history, so, in Mexico catholic conversion took a very complex turn, it was used as a political and more importantly economic tool, at the beginning of the colony the Encomienda system (basically a religiously controlled factory-town-church with a slav... errr, I mean, indentured worker force laboring to save their souls for undetermined ammounts of time) took a protagonist role in procuring control and richess over the land the spaniards were attempting to take control of, whis was a process that took almost 200 years and the use of religion as a political tool was fundamental, indeed I wrote a little bit about the effect it had on former mesoamerican nations like the Tlaxcatecans here, other "allied" nations like the aforementioned tlaxcaltecs and others like the cachiqueles followed the same path and adopted the religion as a kind of compliment to their own cultures.

Catholicism in Mexico is an interesting case study of religious mixing, almost no interpretation of catholicism in Mexico was (or still is in many cases) the same as it was in Europe with catholic priests taking pains to translate their texts to nahuatl and other languages in order to allow them to communicate this utterly alien religion to the people of America, this came acompanied with the usual bans on native religious practices, inquisitorial torture and destruction/genocide of opposing polities (and there are some truly horrifying accounts passed to us in reports and diaries by their perpetrators on both regards), though this was not always the case.

For example, in places that due to geography, political organization or other factors made it impossible for the spaniards to conquer the region, like in Oaxaca, they often opted for strategic marriages and alliances with the dominant groups in the region, such was the case with the Mixtec and Zapotecs, many of which would go on to found noble houses of their own, this obviously with the caveat that they convert to the catholic faith, for them this usually meant integrating this weird icon of a suffering and tortured man who's pain the spaniards seem to revel in, into their pantheon (a relatively common thing in monotheistic religions), which over the years and centuries would mean that their culture would fuse with catholic dogma giving rise to Mexico's unusual variety of catholic syncretism.

So, TL:DR version: Mostly violence but sometimes no, usually as a political and territorial move and always giving rise to unique blends of syncrethic beliefs and customs that would help colour and mantain Mexico's past and current incredible cultural diversity.