sometimes I get an overwhelming feeling I’m doomed to go to hell.
I know that I shouldn’t feel this way as there is no sin the Holy Spirit cannot forgive.
Are there any bible verses or lessons about this?
Thanks
There are three steps to justifying faith:
1. Mental assent to the gospel ("I believe that God is real and that Jesus came and died on the cross and rose again and that those who believe on Him will inherit eternal life"). But this is not enough to justify a person before God. The demons also believe these things, but they are not given saving faith.
2. Coming to God and receiving Jesus Christ as your Saviour and Lord - making a contract between Him and you that because Jesus died on the cross and paid the penalty for your sinfulness, you are going to embrace Him, make Him your Lord and allow the Holy Spirit to lead you the way He wants you to go. This is the act of faith that converts you to Christ and justifies you before God. At this point you are saved from Hell, and have the seed of God's grace in your heart.
But there are many who have taken this step, but don't have the assurance of salvation, and so, like you, still have doubts and fears about whether they are saved or not. Even the smallest spark of grace in a person's heart will get them to heaven in the same way that a full measure of grace will. Some have great faith, and others have the faith just of a mustard seed, but in either case it is the faith that justifies and gets the person to heaven.
3. Assurance of salvation. This is a blessed state that many have come to. They know beyond doubt that they are truly saved and have no fear of punishment and hell. This is a work only the Holy Spirit can do in a person, and it is good to seek God for it through prayer and study of His word. Sometimes God delays giving the assurance because He wants to really make sure that the believer is trusting fully in Christ even though the assurance hasn't come yet. That person may say to God, "I know that I am not fully assured of my salvation yet, but I am holding on to Your promises and I will not let You go until You bless me with the assurance I need."
So, in summary:
Stage 1 is not enough to justify and save a seeker from judgment and hell. Just knowing and believing about God and Jesus in your mind without making a personal commitment to Christ is falling short of justifying faith.
Stage 2 is the act of justifying faith. This is the faith that the Holy Spirit gives the seeker to be able to make a full commitment to Christ to be his Saviour and Lord.
Stage 3 is a blessed and very happy state, but it is not necessary for justification. But a seeker will never receive assurance if he stays at Stage 1. He may or may not receive assurance at Stage 2, but he is definitely converted and justified and in the arms of Jesus. He then can look forward to progressing to Stage 3 when the Holy Spirit decides to give it to him.
If you have made your commitment to Christ based on the salvation promises in God's Word, then you are certainly justified and will not go to hell, but I think that you are somewhere between stage 2 and 3, and have yet to gain full assurance of salvation. As you seek the Lord further through prayer and study of His Word, it will come - although there are precious saints of God who went through their whole lives without assurance of salvation, but found themselves in heaven anyway because they trusted God's promises to them.
A good book to read is John Bunyan's "Grace Abounding To The Chief Of Sinners". It is his path from his conversion to his assurance of salvation, and details his struggles as he went from Stage 2 to Stage 3.