Has christianity become just a culture?

I got to talk to a Muslim brother today for about 30 minutes, he was asking me a bunch of questions for about 30 minutes that nobody could honestly answer, so I said I don’t know. We were joking around, I asked why did the last 3 Muslim people I talk to ask me questions that can’t be answered, then ask me “how do I know I have the only way.” He was cool, we joked around some more. But he grew up in catholic school forever and got turned away from religion because of experiences and unanswerable questions. We got to talking about religions and he said what’s the difference between what he believed and what I believed. I said I believe people are natural sinful, and cannot be good enough to get to heaven. He said people can be good enough to get to heaven, I said we are all sinful and unlike all the religions I’ve studied, Christianity is the only one in which I am saved by the grace of God and not my own actions. I am saved by Gods love , not by my works. I talked about the gospel and who Jesus is, and it surprised me that after being raised in catholic church all his life, he finally understood who Jesus. But that shouldn’t be a surprise because most “Christians” that I’ve met here cant explain their own faith , and their salvation anyways. The harvest is plentiful but the workers are few.