For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Yes, you can convert to a different religion, even Christianity. That's sort of what Rahab did. She knew that if she didn't go over to the Israelites she and her family would be destroyed along with the other inhabitants of Jericho. So she took a step of faith and hid the spies that had come to her house. She hid them on the roof, then lied when the king asked about them, before she cut a deal with the spies.
Listen closely to her reasoning: 'We heard about how God dried up the Red Sea, and what you did to the two kings of the Amorites. When we heard our hearts melted; for the Lord your God is God in the heavens above and in the earth beneath.' (Josh 2). She says 'we' heard about it and 'our' hearts melted, but she said 'I' know that God has given you the land. In other words, she was the only one who believed unto "salvation."
I believe the men were divinely guided to her house. I believe it was decided before she was ever born into the world. There's no other way to explain it except to call it "luck." She "converted," because she heard the "news" and believed God was with the Israelites. She wanted to be with Him, I believe. Who chose whom?
You can't go searching for a God you've never heard of! All who calls on the name of the Lord will be saved. You can't hear of Him without someone preaching. They preach because they are sent. Faith in God comes from hearing about the Christ. (Rom. 10)
Why doesn't all who hear believe? God calls them contrary. Willfully!
The scriptures confuse some. Hebrews 11:31 ~ "By faith Rahab the prostitute did not perish with the disobedient, because she had given a friendly welcome to the spies." It reads as if she earned it because of what she did. It reads as if she's being compared to "those who were disobedient," as if she obeyed something. She wasn't given an order to obey; the others weren't either. She was a prostitute! She wasn't an "obedient" servant of God, she was a prostitute who would lie if she felt she had a reason to lie.
Hebrews 11 is called the 'Hall of Faith.' The people mentioned in it are put on pedestals, but that isn't why we're told about them. "And all these, (hall of faith stars) though commended through their faith, did not receive what was promised, since God had provided something better for us, that apart from us they should not be made perfect" (Heb. 11:39,40). Then Rom. 12:2 explains why they didn't receive the promise. It was because their faith wasn't enough. Jesus is the "founder and finisher of our faith." Without Jesus our faith is incomplete. Abraham's faith was nothing without the shed blood of the Christ. If Jesus had not died on the Cross, nobody's faith would mean a thing!
We can't earn our way into a relationship with God. He either saves us or He doesn't... that's what the scriptures teach. All of them, not just the new covenant scriptures. Two covenants was always God's plan. He didn't come up with the new because the old covenant didn't work. It did...