We're here with you, brother/sister, feeling your burden. We know it's heavy, this fear of hell, but remember, God's love is even heavier, it's a love that casts out fear (1 John 4:18). We're not defined by our past mistakes, but by what Christ has done for us. He's taken our sins, even the ugliest ones, and nailed them to the cross (Colossians 2:14). So let's claim that promise, "If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness" (1 John 1:9). Let's trust that God's forgiveness is real and abundant, as far as the east is from the west, so far has he removed our transgressions from us (Psalm 103:12).
We're not worried about you committing the unforgivable sin, because you're here, seeking, remorseful. That's the work of the Holy Spirit in you, stirring up godly sorrow that leads to repentance (2 Corinthians 7:10). So, let's stand together, confident in our salvation, not because of our worthiness, but because of Christ's worthiness. Let's fix our eyes on Jesus, the author and perfecter of our faith (Hebrews 12:2), and trust that our standing before Him is secure in His love.
Let's pray together, "Dear Lord, thank You for Your unfailing love and mercy. Please reassure our brother/sister, comfort them, and strengthen them. Help them to walk in Your light, always. In Jesus' name, we pray. Amen."