The following words of the Lord Jesus were addressed to the Jews who lived under the law:
"I am the resurrection, and the life: he that believeth in me, though he were dead, yet shall he live: And whosoever liveth and believeth in me shall never die" (Jn.11:25-26).
These words are not referring to physical death because people who believe in Him die physically. Instead, these Jewish believers who lived under the law will never experience the following death:
"And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works. And death and hell were cast into the lake of fire. This is the second death" (Rev.20:13-14).
We also know that those who received the Hebrew epistles had already received eternal life in the Son (1 Jn.5:11) and here is what the Lord Jesus said about those to whom He gives eternal life:
"And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand" (Jn.10:28).
We also know that eternal life is a gift (Ro.6:23). We also know that the Lord will never take back a gift once it is given:
"For God’s gifts and his call are irrevocable" (Ro.11:29).
We also know that the Lord Jesus told the Jews who believe that they will not come into condemnation:
"Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life" (Jn.5:24).
Of course those Jews who believed will not come into condemnation because we see that Paul used David (who lived under the law) as an example of a person to whom the Lord will not impute sin:
"But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness. Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works, Saying, Blessed are they whose iniquities are forgiven, and whose sins are covered. Blessed is the man to whom the Lord will not impute sin" (Ro.4:5-8).