Matt 8:21-22 is referring to this lifetime only. I also don't see any reference to the lake of fire. The bottom line is this, if we are not clothing ourselves with immortality at the first resurrection then the alternative is mortality, death. Nonbelievers will not partake in the first resurrection. Nonbelievers won't be clothing themselves with immortality, rather they will come alive to be judged. Believers will be clothed, nonbelievers will be judged. Their heart will eventually stop beating in the lake of fire. That is the definition of mortality. Death is defined when your heart stop beating. Nowhere in Rev 20:11-15 NIV does it mention being clothed in immortality, it does however mention DEATH. Not to mention "death has been swallowed up in victory" in 1 Cor 15:54 NIV. Do you see the logic....
FIRST RESURRECTION - 1 Cor 15:50-54 NIV I declare to you, brothers and sisters, that flesh and blood cannot inherit the kingdom of God, nor does the perishable inherit the imperishable. 51Listen, I tell you a mystery: We will not all sleep, but we will all be changed— 52in a flash, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, the dead will be raised imperishable, and we will be changed. 53For the perishable must clothe itself with the imperishable, and the mortal with immortality. 54When the perishable has been clothed with the imperishable, and the mortal with immortality, then the saying that is written will come true: “Death has been swallowed up in victory.”
GREAT WHITE THRONE JUDGMENT - Rev 20:11-15 NIV Then I saw a great white throne and him who was seated on it. The earth and the heavens fled from his presence, and there was no place for them. 12And I saw the dead, great and small, standing before the throne, and books were opened. Another book was opened, which is the book of life. The dead were judged according to what they had done as recorded in the books. 13The sea gave up the dead that were in it, and death and Hades gave up the dead that were in them, and each person was judged according to what they had done. 14Then death and Hades were thrown into the lake of fire. The lake of fire is the second death. 15Anyone whose name was not found written in the book of life was thrown into the lake of fire.
- ATP