Though they be liberal, and therefore probably CAN'T use logic, try a logical approach.
1. A firearm is a tool...
Nothing more. It takes a MAN to put this tool to use for either good, or bad. A baseball bat is a tool that can be used to take life. An automobile is a tool that can be used to take life. NONE will take, or SAVE a life WITHOUT a man behind the mechanism.
2. Firearms work BOTH ways...
While MAN may use a firearm to conduct acts of evil, man ALSO uses firearms to THWART acts of evil. The media plays up firearms related crime, however, they FAIL to give the SAME coverage for the PREVENTION of crimes due to use of firearms. While a criminal may use a firearm to rob a liquor store, a law abiding citizen may just as surely protect himself, his family, and his property by using a firearm.
3. Firearms are used THOUSANDS of times a week by law abiding citizens in the pursuit of sport and competition in clubs across the country without incident.
USPSA, IDPA, CMP, Steele Challenge, GSSF, NRA, SASS, all are examples of how law abiding citizens joined in the pursuit of sport and competition embrace firearms as tools of discipline, skill, and tradition, and NOT of crime and negligence. Take them to a good club match and let them experience the cameraderie and the safety measures employed by responsible gun owners.
4. The right to keep and bear arms is a RIGHT we have as AMERICANS thanks to the foresight of our founding fathers.
Our founding fathers were smart and had uncommon integrity and great courage. They KNEW how governing bodies can, and WILL, abuse their power over citizens. They KNEW that the ONLY way to GUARANTEE that citizens could defend themselves from INTERNAL, or external threats, was to ensure they had the RIGHT to keep and bear arms.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed"
While there is much contention on the liberal side about WHO and WHAT a militia is, there is NO doubt in my mind, or in our founding fathers mind, about who the militia is...
It's YOU. And ME. And EVERY other American citizen.
WE are the militia. WE NEED firearms to ensure the security of OUR free state.
Don't believe me?
Check out the militia created by some of our Korean American citizens during the LA Riots. They sent out a call to arms to support and defend their businesses that were under attack.
Where were the police?
Where was the national guard, or the Army?
NOWHERE to be found.
There are countless examples from past, and present, of citizens using their RIGHT to keep and bear arms to defend themselves, their families, and their property.
Bottom line: Firearms are NOT evil. MEN are evil, and the firearm is one of the most effective tools to defend ourselves from those evil men.