Believers know their faith is confirmed through the evidence of faith in Christ and the assurance given by the Holy Spirit.
The confirmation of faith is evidenced in the life of a believer by the presence of the Holy Spirit, who works in their hearts to regenerate and establish them in Christ. In 1 Thessalonians 1:5, Paul explains that their faith was validated through the effective working of the gospel, which was evidenced by the transformation in their lives and their response to salvation. Assurance comes from relying on the perfect work of Christ, as believers are not saved by their faith but by His faithfulness (Romans 5:1). Thus, the assurance is grounded in the object of their faith, Jesus Christ, and not in their own works.
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