In regards to Copts have tatoos of crosses...
In times of heavy persecution it would be extremely easy just take off the cross worn around ones neck, and try to stay below the radar. Whereas if you have a cross tatooed on your forehead you can't just take it off. Every one will see it, you will have to answer for it [to your persecutors], and may very well lose your life over it. If it keeps one from succumbing to persecutions, then so be it.
And on another point, and at the risk of sounding like an apologist for pagans...
Not all the pagans did or held to was bad, just kinda misdirected. Much as pagans did at their religious festivals, we also have a sacrifice and a common meal. The pagans believed that their ancestors became gods when they died, so we also believe that we will by Grace become what Christ is by nature, ie godlike.
Just some thoughts