Revelation7:3

The seal serves to set them apart from others who do not have that seal, and to show ownership and the protection that the owner will provide for his people.

This seal need not be a physical thing; in fact, since we are talking about spiritual issues, it is most likely not something physical. God looks at the heart. If this seal were something visible, people would try to replicate it artificially. As something that distinguishes between groups, it can be an aspect of life and testimony that separates us from those who do not follow Christ. For instance, the fact that a believer is willing to take a stand for Jesus in the midst of threats and possible martyrdom marks him as different than those who are not willing to do this. Likewise, the purity that God gives, and which the believer maintains, is a type of seal; it sets him apart from those that do not exhibit purity.

Yet the idea of a seal is also about ownership and protection. This pledge of protection serves as an encouragement to the faithful believers.  What might the seal be? Once again it could be the purity of life. This is what God looks for, and when He sees it He calls that person His own, and is committed to protecting His own. Such purity comes from God, but it requires effort, focus and discipline on our part to maintain it, along with help from the Holy Spirit.

While ancient covenants required a sign of the covenant and that sign was often a mark on the skin in a prominent place like the forehead, this is for the benefit of the one being sealed, more than for others. Just like the phylacteries of the Old Testament, this is a reminder to the believer of his commitments and where his encouragement comes from. Recall that the sign of the Former Covenant was not something visible to others, rather it was circumcision, a reminder to one’s self of the loyalty he professed. While the mark mentioned here will be used by God’s angels to know the difference between the rebellious and the faithful, the use of the word “forehead” points to personal focus and various benefits such focus brings. The point here is that this difference, produced by the inner transformation only God can effect, and the believer’s perseverance, is itself a type of encouragement for the believer. The very thing that makes them different, the thing that attracts attention to them and draws the ridicule and persecution from their antagonists, is also intended to be a source of encouragement to the believer. He knows he is on the right track when such persecution comes. They opposed, persecuted and killed Jesus, so when they do the same to us we know we are heading the right direction. Someone once said, “if you haven’t met Satan face to face, you’re going the same direction he is.” So rather than wishing we did not stand out, we should be glad our purity stands out as something different. If we are striving to fit in with the world, that is when we are in trouble!