John 5
24 “Most assuredly, I say to you, he who hears My word and believes in Him who sent Me has everlasting life, and shall not come into judgment, but has passed from death into life.
Since believers are already possessing eternal life and won't come into-under judgment, they cannot logically be liable to the second death.
That is what Christ is emphatically teaching. The judgment they do come under is one for rewards or the lack of rewards, but their eternal life will never be taken from them by any kind or aspect or part of the Day of Judgment. Not so with unbelievers.
And we know unbelievers do not possess eternal life as Jesus is way truth life, and they don't know Him, Christ does not know them, and they do not obey the gospel.
Scripture in the NT church teaching by the apostles say the unbelieving will be punished with everlasting destruction and separation away from God and Christ when He returns. This is why, the teaching to the church is clear in the church letters, while Revelations is a vision and not figurative, so it must not be relied upon for doctrine.
2 Thess 1 is written so as to not be figurative, and meaning is clear. Any trying to figure out what Revelation means must agree with what is taught by the Spirit here.
2 Thess 1
1 Paul, Silvanus, and Timothy,
To the church of the Thessalonians in God our Father and the Lord Jesus Christ:
2 Grace to you and peace from God our Father and the Lord Jesus Christ.
God’s Final Judgment and Glory
3 We are bound to thank God always for you, brethren, as it is fitting, because your faith grows exceedingly, and the love of every one of you all abounds toward each other, 4 so that we ourselves boast of you among the churches of God for your patience and faith in all your persecutions and [
a]tribulations that you endure, 5
which is manifest[
b] evidence of the righteous judgment of God, that you may be counted worthy of the kingdom of God, for which you also suffer; 6 since
it is a righteous thing with God to repay with [
c]tribulation those who trouble you, 7 and to
give you who are troubled rest with us when the Lord Jesus is revealed from heaven with His mighty angels, 8 in flaming fire taking vengeance on those who do not know God, and on those who do not obey the gospel of our Lord Jesus Christ. 9 These shall be punished with everlasting destruction from the presence of the Lord and from the glory of His power, 10 when He comes, in that Day, to be glorified in His saints and to be admired among all those who [
d]believe, because our testimony among you was believed.
11 Therefore we also pray always for you that our God would count you worthy of
this calling, and fulfill all the good pleasure of
His goodness and the work of faith with power, 12 that the name of our Lord Jesus Christ may be glorified in you, and you in Him, according to the grace of our God and the Lord Jesus Christ.
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And the above also heartily agrees with the sound words of Jesus Christ written in many places regarding who has eternal life and who does not.