So how can anyone expect someone that doesn’t believe, to ever believe? Can people just decide to believe, or does it come from God? If it comes from God, why doesn’t everyone believe the same?
Really good questions and ones that require some consideration.
Someone who doesn't believe in God is likely not to be persuaded by what others hold as Holy Scripture.
May I recommend that you read a book by C.S. Lewis.
It's called Mere Christianity and it spells out in a very simple, logical way Lewis' belief at a base level about not only the existence of God, but in his belief in Jesus as the Son of God.
If these questions about the basis of faith are real, and I believe they are, you might find this book a good insight on how people come to a point of faith from a previous point of atheism, like Lewis did.
So how can anyone expect someone that doesn’t believe, to ever believe? Ans: God draws them to Himself.
Can people just decide to believe, or does it come from God? Ans: It all comes from God, even when it appears to be entirely one’s own decision.
If it comes from God, why doesn’t everyone believe the same? Ans: In a word, because of Sin. God’s will for us is to be conformed to the image of His Son, Jesus Christ, but this does not happen instantaneously. Conversion is a decision followed by a process. Think of your life as a bucket of dirty water: if you continuously add clear ice to it, the dirt will be diluted more and more, unless you put more dirt in. Eventually what you will have is pure water.