IMO do what you think Jesus would do. If you think it's to stay off of FB and engage with people on another site or in person, go for it. If you think it's to be on FB standing for truth, do it. If you think FB is a NSA tool that experiments on people, don't use it and make others aware.
I have a FB page, I know that it is a toll used by the government to keep tabs on me and try and change what I believe to be true. I use FB to fight abortion, make my family and friends aware of the atrocities of PP and help them realize that there are better options for women's healthcare, I connect with other people who do the same, and I also use it to keep in touch with my mother, who doesn't always have a phone and lives far away from me.