Personally Linear, I think everybody will know about the mark of the beast when it happens and I do not believe anybody will accept it in ignorance. It will be a decision that is made that one either stands for Christ, or they accept the Antichrist in place of Him. However, will there be exceptions and mitigating circumstances for some? Perhaps. I don't know that, only Christ knows this. However, will a person even be "able" to turn to Christ after they accept the mark? Again, I don't know. However, I also believe that Christ will not abandon those whose intentions are good and I believe those who make an inward decision for him but are afraid and intimidated will be given special graces and courage from the Holy Spirit. One only has to remember the fear of the apostles and how they abandoned him (all but one), because they were scared of being killed if they were found out. Yet let us not forget what happened to them in the upper room with the Holy Spirit. Tongues of fire came down upon each one of them. Not only were they relieved of their fears, but they ran out and began to preach from the roof tops (literally). Saint Peter's self digust at his own cowardice at running from Christ in the hour of need to 'save his own skin" were completely turned around - literally, by the Holy Spirit within him when he was threatened with death. He asked to be crucified upside down, as he did not feel worthy to be crucified in the same manner as Christ. The prospect of such a death, let alone the style of his crucifixion were a testament to that also. As well as the effects of their preaching, which was due to the workings of the Holy Spirit through them.

So we must remember God's hand in all these things. As Satan intensifies and reaches the climax of the tribulation, so too will the Holy Spirit! And to be honest, I have no doubts God will be there for all of us who reach out to him in that hour of need.