[Jan_Sobieski]

Do reformed theologians believe that Christians are going to increase around the Globe and take over the world for Jesus? “Of the increase of His Government there will be no end...” (Isaiah 9)? Additionally, don’t they believe in “once saved always saved”?

If so, why would they even care about a “mark”?

[circlecity]

I know of no reformed post millennialists although there are probably some out there. That school of eschatology really faded out in the 60s. There are many of the reformed school who believe in the growth of ungodly government attempting to impose itself globally- both scripture and history support this and Rome is an excellent example presaging this. Yes, if you believe God can see into the future once saved always saved is a logical consequence. If one takes the mark it shows they were never saved which is why you don’t take it whatever your theology.