The rest to be entered into is still future. The sharp two-edged sword is the word of God, but also a literal sword of God’s wrath against His enemies. Christ returns to defeat Israel’s enemies, then gives Israel rest from those enemies.
When Hebrews 4 speaks of entering into rest, it isn’t talking about eternal life; it is talking about Israel entering into the land promised to Abraham, Isaac, and Jacob and resting because their enemies are defeated. Also examined is the multiplicity of gospels preached throughout the Word of God.