My Life Ethics

In my reading right now I'm studying a story with an Anti-Christ in it where he is going around to people telling them that there is no Christ.

For no man can know of anything which is to come...How do ye know of their surety? Behold, ye cannot know of things which ye do not see; therefore ye cannot know that there shall be a Christ

He was also telling them it doesn't matter what you do (sin or live righteously) bc "that when a man was dead, that was the end thereof." But for me, it does still matter. Hypothetically, even if death was the end, that doesn't change the kind of person I am. I'm not going to start living life with no caution just bc of what this one man says or if this would become truth (it's NOT). If everyone lived that way, chaos would follow. My life ethics wouldn't change. I obey the law bc they protect me. I honor my marriage vows bc religion or no religion...they mean something and it is recognized by the law. I will still raise my daughter with love, compassion, and patience (as much as possible) bc I love her and she deserves it!