No, how you configure your firewall keeps your network safe. This may seem to be an equivalent statement, but it's not. While the importance of firewalls cannot be overstated, even the most secure firewall available won't provide security if error, ignorance, carelessness, apathy, or company policy results in an insecure configuration. I've seen this so many times it would be humorous if it wasn't so dangerous and costly. Review your firewall logs frequently, re-examine your firewall rules, and have an impartial 3rd party audit your network security. Compare your network security policy with your implementation.