Question: How can I know if I’m elect?
Response: First of all, the Bible does not teach justification by election, but that our just standing before God is by grace alone in Christ alone as evidenced by our faith. Election does not save but is a blueprint of what God intends to do in time in Jesus Christ. If you are a sinner who has cast aside all self-righteousness and trusts in Jesus Christ as your only hope for salvation, you can know, based on God's certain promise that He has done a work of grace in you, that your sins are forgiven and are, therefore, counted among the elect.
God commands all men everywhere to repent and believe the gospel. But when someone actually comes to faith in Christ we can know from Scripture that it was God who, in His great mercy, opened their blind eyes, unplugged their deaf ears and gave them a new heart to understand and obey the command (Deut 29:4, 30:6; Matt 16:16-17; Rom 9:15, 16). When God removes the scales from our eyes, when He turns the heart of stone to a heart of flesh (Ezek 36:26) there is no longer resistance because the heart is no longer hard like stone. All resistance has been disarmed.
"Our Lord did not come to tell us what we have to do in order to save ourselves; He came to save us... The Christian doctrine of salvation and redemption is this - that Christ Himself is the salvation."- Martyn Lloyd-Jones
Simon Peter replied, “You are the Christ, the Son of the living God.” And Jesus answered him, “Blessed are you, Simon Bar-Jonah! For flesh and blood has not revealed this to you, but my Father who is in heaven. - Matt 16:16-17
Jesus declares Peter's confession was supernatural. That means the fallen sinner's faith in Christ is not self-generated but a work of creation (regeneration) which the Holy Spirit broods over until hatched, so to speak. And since it is a work of God we have confidence that He will finish what He began (John 6:37-39).
Recommended Resources
Studies on Saving Faith (free eBook) by A. W. Pink
Assurance by J. C. Ryle
Reflections on Assurance by D. A. Carson
The Assurance of Salvation (Study Guide) by R. C. Sproul