Is this normal in Japan or It’s happening with others too?

It was that day when I came home from school and was doing my usual stuff. It was almost 4 o'clock in the evening, and I was still in my school uniform, and as I was about to change clothes, the doorbell suddenly rang. At first I thought it was the same good old (宅急便) courier service (since couriers come to my home most often). Yet this time it's different. And being the complete idiot I was, I opened the door recklessly (which I mostly recommend to all not to do that unless you peeked through the keyhole on the door to identify the person), and I saw two people (I am not going to say their genders with due respect to their privacy). We exchanged greetings with "konnichiwa." Honestly, the first thing that came to my mind was "Oh, new neighbors!" but I don't see any souvenirs on them, which is strange. They asked if my parents were at home (again, I was in my uniform), and I told them they were outside at the moment. Then one of them introduced themselves as Christians and started a short speech on "receiving" (受ける) or something like that. After finishing the boring speech, they asked for my thoughts on it. I was bamboozled, and as your typical Japanese learner, I replied with the good old Japanese solution, "そうですね!" (That's right.) They seemed to notice I wasn't Japanese, and they asked which country I originally resided in. I told them I was a … person after that. They asked for my religion, and I told them I belonged to the … religion. They replied with, "Oh! That's nice." And then we ended our conversation with sayonara. After that day they came again this month, which made me ask my Japanese sensei about these "people", My sensei told me, "Those are frauds who need donations in the name of Christ; they will try to influence you to join them." Sensei continued with, "You are free to choose which religion you want to follow; those people will never let you change religion once you join them." And that "these people" came to Sensei's house more often than mine. Sensei said that if they come again, don't open the door and make an excuse, saying in English that you don't know Japanese, or just be quiet After that, they'd leave you alone. What are your thoughts on this? Are "these people" coming to your house too?

EDIT: I am not saying Christianity is a problem here. What I'm trying to say is that many people have their own beliefs, and I don't want to cause huge havoc on this matter with Christianity. I respect it as well as other religions. That's it.
"Those people" can possibly be in a cult, as mentioned in the comments. Stay safe

by Prior-Pea9372