In Revelation 7:1-3, four angels are holding back the four winds of destruction, Then a fifth angel "ascends" with the "seal of the living God." He then commands the other four angels to continue holding back the destruction until ALL of God's people are sealed.
The seal, therefore, was not available from the beginning. Furthermore, people who are already believers are sealed.
In contrast, the seal Paul wrote about seems to be associated with conversion.
To clarify, I don't find "seal" in 1 John 4. But the answer is: no, the seal in Revelation is different.
2 Corinthians 1:21-22 :
it is God who establishes us with you in Christ, and has commissioned us. He has put his seal upon us and given us his Spirit in our hearts as a guarantee.
This is a seal of God's commission, apparently to spread the Gospel. This seal, as well as the seals in Ephesians was already given in Paul's time assuming that Paul is indeed the author of Ephesians. So generally, Christians already had received this seal long before the events in Revelation.
The seal in Revelation, on the other hand, has not yet been given, even to the 144,000:
Do not harm the earth or the sea or the trees, till we have sealed the servants of our God upon their foreheads. And I heard the number of the sealed, a hundred and forty-four thousand...
This is not a seal of commission; it is a seal of protection against coming disasters. Its protective function is described in Rev. 9:4:
they [the scorpions] were told not to harm the grass of the earth or any green growth or any tree, but only those of mankind who have not the seal of God upon their foreheads...
So the answer is simple: the seal in Revelation 7 is a different seal than the one referred to in various NT letters.
