'1Sa 2:27 And there came a man of God to Eli and said to him, “Thus says the LORD, ‘Did I indeed reveal myself to the house of your father when they were in Egypt subject to the house of Pharaoh? 1Sa 2:28 Did I choose him out of all the tribes of Israel to be my priest, to go up to my altar, to burn incense, to wear an ephod before me? I gave to the house of your father all my offerings by fire from the people of Israel. 1Sa 2:29 Why then do you scorn my sacrifices and my offerings that I commanded for my dwelling, and honor your sons above me by fattening yourselves on the choicest parts of every offering of my people Israel?’ 1Sa 2:30 Therefore the LORD, the God of Israel, declares: ‘I promised that your house and the house of your father should go in and out before me forever,’ but now the LORD declares: ‘Far be it from me, for those who honor me I will honor, and those who despise me shall be lightly esteemed.
In 1 Samuel 2, there is an interesting scene in which God revokes His promise of an eternal house for Eli. This is fairly unambiguous by the wording of the text. God had “promised” but now that promise is “Far from” Him, and a new rule supersedes the previous.
Parallel concepts are found in God’s eternal kingdom, originally planned for Saul, but then given to King David. Through David’s life and through the lives of the following Kings, God warns that the eternal kingdom can be cut off if the recipients are evil.
When we reach the New Testament, we encounter claims of eternal life. Modern Christians claim that this means that individuals become robots. No longer can they sin, but they will forever be in heaven without a chance to rebel. Is this a warranted conclusion from the use of the word “eternal”? Did eternal take that meaning with Saul, David, or Eli? What discludes a conditional eternity rather than a deterministic eternity? Are there any eternal promises in the Bible of the type the deterministics can use as an example?
The most eternal promise found within the Bible is the unilateral promise to Abraham to make of Him a great nation. Malachi 3 claims of this promise that God will not change on it. Hebrews 6:18 claims that in this promise it is impossible for God to lie. The Jews were confident that this would mean they would never be cut off completely, but John the Baptist counters otherwise:
Mat 3:9 And do not presume to say to yourselves, ‘We have Abraham as our father,’ for I tell you, God is able from these stones to raise up children for Abraham.
Even if every son of Abraham rebelled, God has innovative options that are not reliant on mankind’s continued obedience. With this being the case, there is no reason to think that both mankind is granted eternal life and that the eternal life cannot be revoked if mankind chooses to rebel. John is under the impression that mankind still has the ability to reject God even if it threatens God’s promises.
source: Chris Fisher, “Eternal Security” (realityisnotoptional).