"But now a righteousness from God, apart from law, has been made known, to which the Law and the Prophets testify. This righteousness from God comes through faith in Jesus Christ to all who believe. There is no difference, for all have sinned and fall short of the glory of God, and are justified freely by his grace through the redemption that came by Christ Jesus." Rom 3:21-24God saves us from the guilt of our sin and ultimately from our innate sinfulness that we may be acceptable in His sight. We are delivered from God's wrath in these two illustrations of water and fire.
Consider the waters of Noah's flood. The waters represent the wrath of God. Noah was saved by being immersed into the ark which was Christ, the ark being immersed in the waters just as Christ takes the brunt of God's wrath while we rest safely in Him. "once the Divine longsuffering waited in the days of Noah, while the ark was being prepared, in which a few, that is, eight souls, were saved through water. There is also an antitype which now saves us——baptism (not the removal of the filth of the flesh, but the answer of a good conscience toward God), through the resurrection of Jesus Christ" 1Pet 3:20,21 (nkjv)
So also fire is representative of God's wrath as in Rev 20:15 "If anyone’s name was not found written in the book of life, he was thrown into the lake of fire." We see in Daniel chapter 3 that three of Daniels friends who refused to worship an idol were thrown into a fire, but not burned. Rather the king said, "Look! I see four men walking around in the fire, unbound and unharmed, and the fourth looks like a son of the gods." Daniel 3:25 This 4th represents Christ who walks with us into the fire and prevents us from being harmed. The earth along with the ungodly will be destroyed by fire as it is written, "the present heavens and earth are reserved for fire, being kept for the day of judgment and destruction of ungodly men." 2Pet 3:7 "But in keeping with his promise we are looking forward to a new heaven and a new earth, the home of righteousness." 2Pet 3:13