Revelation 15:2 says, “And I saw as it were a glassy sea mingled with fire, and those who had come off victorious from the beast and from his image and from the number of his name, standing on the glassy sea, having harps of God.” We may call those mentioned here the late overcomers, the believers who pass through most of the great tribulation and who overcome Antichrist and his worship. These are those referred to in 14:12 and 13, who will be martyred under the persecution of Antichrist, then resurrected to reign with Christ in the millennium (20:4).
The late overcomers will overcome the beast, his image, and the number of his name. Although they are slain by Antichrist, in the eyes of God they are victorious. Because they will overcome at a later time, we speak of them as the late overcomers.
Verse 2 says that the late overcomers stand on the glassy sea. This firstly signifies that they have been resurrected from the dead.
Secondly, it signifies that the late overcomers have been raptured to the heavens. In 4:6 there were no people standing on the glassy sea, but the late overcomers will stand there after they have been raptured to the heavens.
In verse 2 the apostle John “saw as it were a glassy sea mingled with fire.” The fact that the late overcomers stand upon the glassy sea also indicates that they are above all the judgments of God, which have nothing to do with them.
This glassy sea is not of water, but of fire. According to the Bible, God exercises His judgment over the rebellious earth, angels, and mankind first by means of water and then fire. After God judged the rebellious angels and the earth with water, this judging water became the sea. The lake of fire will be the consummation of all the fires used by God to judge the rebellious things. Thus, the two means used by God to exercise judgment, water and fire, will be mingled together, firstly as the glassy sea and finally as the lake of fire. The glassy sea, the precursor of the lake of fire, will develop into the lake of fire.
Since the deluge, God, in accordance with His promise not to judge the earth and living creatures again with water (Gen. 9:15), always exercises His judgment upon man with fire (Gen. 19:24; Lev. 10:2; Num. 11:1; 16:35; Dan. 7:11; Rev. 14:11; 18:8; 19:20; 20:9-10; 21:8). God’s throne of judgment is like the fiery flame out of which a fiery stream issues (Dan. 7:9-10). The flame of God’s judging fire sweeps all negative things in the entire universe into this glassy sea, which eventually becomes the lake of fire (20:14), the aggregate of all God’s fiery judgment.