They think, “Jesus was cool. I like him, and I’m gonna try to be like him.” Kind of like their guiding light is what would Jesus do? But there isn’t a focus on identification, recruiting others, judging others based on their religion, fear of God, fear of punishment for sinning, respect for clergy as an authority, rituals, worship, etc. Basically, just the example of Jesus’ life.
inb4: Christian lol!! got em!
Adherence to a moral standard is secular, even if the source is a mythological text that is the foundation of a religion.
Keep in mind that the religious figure of Jesus predates Christianity.