We know we are saved by believing in Christ as our one mediator and embracing His truth.
The assurance of salvation for believers comes from faith in Christ alone. As noted in Romans 8:29-30, those whom God foreknew He also predestined, called, justified, and glorified. To ascertain if one is among 'the you all' mentioned in Revelation 22:21, the key question is whether they believe in Jesus as the Lamb of God and accept that salvation is only through Him. When individuals acknowledge their sinfulness and place their faith in Christ's work, they find their name written in the Lamb's Book of Life and thus are assured in their salvation. This assurance is grounded not in their merits but in the grace of God through faith.
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