I was tormented gravely by the thought that I could lose my salvation.

I was raised as a Christian to believe in Eternal Security, once saved, always saved, but I was also raised to read the Word of God, the Bible. After I had read and read and read, I began to have doubts. On top of that the wonderful manifest presence of the Lord vanished completely. I got so angry with God that I threw the Bible against the wall in great anger and left it there on the floor for very long days.

I had a fear of God, but my belief in Jesus slipped badly. I was not sure about Jesus. I was in the Dark Night of the Soul and felt that God had abandoned me. I was miserable for decades.

I came to a point in my life when I wanted to die. So I looked at my options and death seemed to be the only option. But a thought came to me, God. The Holy Spirit had not vanished. He threw out a life line to me. I grabbed it and immediately, though I was still in my dying body, I suddenly had a manifest presence of my heavenly Father. He loved me in spite of me. In fact the thing I remember is His great, great love. After a week of this marvelous experience, the Father asked me point blank: "What about Jesus?" I said, "OK, I believe in Jesus Christ."  Now I wanted to finish dying and to be with my heavenly Father, but God said NO. I woke up to life on earth, and my body recovered. I even picked up my Bible that I had thrown so violently against the wall and began to read it again.

Along the way I put a serious question to the Lord. "Can I lose my salvation?"
I actually shouted this to the Lord. I said, "In places it seems You teach security, but in other places in the Bible You teach some really scary stuff."  In my frustration and torment of soul, I did not care who heard me. I had shouted this with all my might. All my anger, my frustration, and torment came pouring out in that prayer, so that I sat there tired out, but relaxed. Suddenly the Lord gave me two scriptures from the Bible. Bam, bam, just like that.

"For the Lord will not cast off his people,
neither will he forsake his inheritance.

and

 For if we would judge ourselves, we should not be judged.
But when we are judged, we are chastened of the Lord, that we should not be condemned with the world."

Those two scriptures settled my heart. Truth from God will do that. 

Since then God  has given me understanding to allow Him to sanctify me in a long painful process, without rebelling. God's grace. God never took me out of the Dark Night of the Soul, but He sent His light. Actually He was there all along, but I could not perceive it. What God actually did was to transfer my faith from my soul to my spirit. God at work.