I have been a Christian since about four or five, although I had a period last year of identifying as atheist then Taoist. People say a true Christian would never do that. That I wasn't saved before, or if I was saved I've crossed an unforgivable line. Could I have been saved? It scares me so much, if I wasn't saved, and I blasphemed and had those soul-selling thoughts does this mean I am irreversibly condemned to hell? I was so sure I loved God growing up, I want to repent and have the love and trust I had before, but can I not be saved? Am I saved? I hate that I ever strayed. I was so depressed, I ran a blog of uplifting things that I noticed most came from Buddhism, which led me away. I never was convinced by Buddhism but I see what a lie Taoism was now. I just want to be saved. I want to be at peace. I need mercy. I hope I am not reprobate or beyond forgiveness. Is there any way that doubt doesn't mean I wasn't saved? Or do I even have a chance? What do I do?
You can't have repented and come back to the Lord unless the Holy Spirit drew you. IOW yes you are saved.
The Early Church wrestled with the problem of Apostaty, of those Christians who denied Christ, and later wanted to return to the Church. There was a minority who said, Absolutely not! But they were overruled. If those who apostatized confessed their sin and did penance, they were allowed back into fellowship, same as with any other serious sin.
I did the same thing as you. I too had spent my whole life as a baptized and believing Christian, very close to Christ. I walked the walk, and I knew the Lord. However, I became very disturbed over the Church's violent past, such as the conversion of the Saxons to Christianity at the point of the sword and the slaughter of those who would not. By far the biggest horror in my eyes was the Church's abuse of the Jews, discrimination, harassment, torture, and massacres. I came to feel that no true Church of God could do such things. And if the Church was false, then the Canon of the Bible which the Church put together was false, and the Christ who established the Church was false as well. With terrible sadness, I left Christ. I ended up exploring my roots in Orthodox Judaism.
But the more time that went by, the more I missed Jesus. I missed Eucharist. I missed confession. I began going back to Mass. Eventually I made my confession, "Lord I believe, help me my unbelief," and came back. I was determined to CHOOSE Christ even if my brain objected. I would do Christian actions and I would profess Christian beliefs until it WAS natural. I would live my life "AS THOUGH" I believed. At first things were really difficult. I couldn't sasy the Creed without choking on it. But I just kept on, making that conscious choice. Time went by, and I found myself saying Christian things more and more often spontaneously. Eventually I felt comfortable with the Creed, worshipping Christ, praying again, the whole nine yards. Today I am back again, feeling close to my Lord and Savior Jesus Christ.
I believe my Apostasy was a mortal sin, that it killed a part of my soul. It altered my spirit so that it was far more difficult to return to Christ. But though I had abandoned Jesus, I don't believe he had entirely abandoned me, or else the Holy Spirit would never have left me with that hunger.