Lifelong_sinner,
For many, many miserable years I tried to make myself believe in Jesus, while at the same time I wasn't sure if the bible was true or if God was real. I thought there was no way anyone could know for sure that he/she was really "saved."
After many years of struggling with the matter, after reading books about the bible & about how to "believe in Jesus," I was still confused, miserable, fearful, & uncertain about the truth of the bible.
My struggle ended one night when I just simply gave up on trying to understand it all and asked the God who I wasn't even sure existed if He would show me the truth about believing in Jesus. Next, I found a bible and opened it to the Gospel of John and started reading. (That was the first time I had ever opened a bible out side of being in a church.) As I read the words in the Book of John I soon realized that God was showing me the truth about Himself & about who Jesus is. By the time I got to the end of chapter 6 I was convinced that God is real, that the bible is the truth, and that Jesus paid the penalty for all my sin when He went to the cross. I put my faith in that message that night & called out to Jesus for Him to give me the new life in Him that only He can give.
I can only explain what happened to me that night by saying that I took me eyes off of myself and looked to God for the answer to my struggle, and God's Holy Spirit took over and gave me the spiritual light I needed so that I could "believe."
I found a peace that night that is impossible to explain to anyone who have never experienced the peace that only God can give. Today, 40+ years later I still have that peace.
My suggestion to you is that your answer is in God's Word. The Book of John, Gospel of John, and the Book of Romans are two books I would recommend that you read. Read them more than one time if you need to do so, and ask God to show you whatever it is you need from His word to convince you to believe.
And, yes, ask your preacher friend for help, but if he tells you that all you need to do is say a prayer "in Jesus' name" then I suggest you seek counsel from other Christians, and read the Gospel of John.
I have a favorite hymn, "It Is Well with My Soul" and the third verse says it all to me:
My Sin Oh the Bliss of this Glorious Thought
My Sin Not in Part but the Whole
Is Nailed to the the Cross and I Bear it No More
Praise the Lord Praise the Lord Oh My Soul
It Is Well with My Soul, by Horatio P. Spafford
Regards, John