I wouldn't teach my children that there was no God. I can only tell them what my views and opinions on the topic are and why I have come to the conclusion I have.
As for teaching them about Christianity (the religion of my family), I'm undecided. The fact is that that religion often plays an important part in a culture, and kids will want to know about their grandparents, great grandparents etc... So for them to understand who their culture and ancestors, I feel it somewhat necessary to teach them about the religion.