Is using Facebook halal or haram in islam?

There are several schools of thought about this, so it's best to ask your own Iman.

The basic relation of using "Asbaab" is with the strength of Emaan in respective individual. The Strong believers avoid such stuff by their own reason for ex. Safety of vision, which has direct impact on emaan, But, people who use FB with correct Niyat of Spreading Islam, it is okay, but Avoiding self from all the non-recommended things is not that much easy, such users get affected by other material on FB. So, my answer is "using FB is NOT Recommended in ISLAM", one can't say Haram/Halal. This is my opinion Ulema can tell respective indivisual regarding the same according to observations of him/her.

Assalamu Alaikum

Many say there is nothing wrong with it. There are MANY Muslims on Facebook. But there are some who believe it not to be OK.
I would talk to your Imam about it like Ben said.