I haven't read the above posts yet, except the first one, but I wanted to go ahead and respond to the question first.
Do you believe the gospel because it's the Truth or because you were taught it's the Truth?
Because its truth. I think it boils down to whether you've had a personal encounter with God, that either led you to believe or as you have begun to walk with him. Jesus said that blessed are those who believe without seeing, but he still showed his hands to Thomas and let him touch his side. I think in my walk with God, he has been more than gracious with me that as I first began to speak to him, he filled me with joy, and gave me visions and dreams, and experiences where he spoke to me so I knew it was him. When I was a baby Christian, it cemented me in my faith.
It was what people said about the truth of God and the reality of God that made we want to seek a relationship with Him in the first place, but other people's faith didn't make me just want to glom on and go with flow, but God gave me this "I have to see it real for myself" attitude. In the beginning, when I first started seeking God, I almost refused to go by faith, so to speak. I was like "God, you have to show yourself to me, I want to know who you are" and when he did that was it, the word was confirmed for me.
More simply (and perhaps more importantly), its also truth, because I remember those times that I've trusted God and his word has proved true. Having done so helps in those times, when God seems silent to my spirit and all I have is the word God. In particular, I remember a time where I was just seeking God to meet him, to encounter him, and God convicted me of a sin that I had been lying about something to my peers. I repented of the sin, but God told me clear as day that I had to confess it to them. What amazes me and by God's grace was that I didn't hesitate, I just asked God to give me an opportunity and I would do it. I went to a prayer meeting that morning, and the leader asked near the end if anyone had anything to share. He never ever ever did that before and never again. I was lilke "wow" when he asked. But I spoke up and confessed my sin. And the best part was that what I was worried about didn't happen. They didn't reject me or chastise me and that was like turning point for me trusting my God.
If you were born in any other country around the world would you still be a Christian? (or would you be a Muslim, Hindu, etc - I know there's no way to truly know...but what do you think?)
I go back to what made me first want to seek him, and that was being around people who had real relationships with God. I had actually never heard that Christianity was a relationship with God, until college, even though I had been in the church when I was small. There was just something different about them (the Christians I knew) about the way they treated me and they treated each other, and the love of God they talked about and his grace and mercy, I wanted that. I was hungry for life when I got saved, had gone through some depression. To answer the question, maybe. I certainly would not have found God on my own, the only reason I started looking was because my Mom suggested I look for a campus ministry because I was so depressed. But then I actually did, so God drew me to himself. So, perhaps more likely than not, other religion in my life might have caused resistance to the Gospel, but if you're dying or thirsty and need of drink of water and you're willing to admit it, God can move.