@Zmaj
“Because what use is being good if there's no reward, right?”
Let me be clear, I applaud anyone who does good in that world regardless of their motives. A Muslim who gives 2% of his wealth to the poor is to be commended for this in my opinion. What I took your quote to mean though was that someone who does good with no expectation of a reward is more altruistic or better than one who expects good in return. On the surface, it is true. Ironically, once you give voice to it, you lose it. Once you point out “Hey I’m not getting a reward when I’m a good boy (so, I must be a better boy than you)” your reward becomes lording it over the other guy and feeling superior. This is precisely what Jesus was preaching against with the Pharisees. I don’t usually quote scripture, but to give a perspective Luke 18: 9-14 speaks to this.
“The notion of a reward in heaven is central to Christianity.”
Yes, it is. You are right about that. Keeping in mind the above point though, it is easily misrepresented.
“It is simply a business. Whether you invest good deeds or faith in Christ is irrelevant for the basic mechanism at work here.”
Here is where we disagree. You’ve stated that this is a business arrangement. I contract with God and fulfill my quota of good boy points. When I kick off, I hope for the best. God may go back and say “Hey CA, remember March of 2017 buddy? You were low on your good deeds that month man. Eternal perdition for you, sorry.”. That is a common misconception of Christianity, actually it is what Joel Osteen sells (albeit in reverse).
As a Christian, I do not find your criticism compelling because it is based on a skewed perspective. Again, I don’t usually quote Scripture, but since the very workings of Christianity are the question here. Scripture is the best way to decide what is and is not Christian. Ephesians 2:8 states “For by grace you have been saved through faith. And this is not your own doing; it is the gift of God.” So, explicitly, it is stated that my good works count for nothing. I am not capable of buying my way into Heaven. Still my good works are expected to fulfill Christ’s commandment “Love one another as I have loved you” (John 13: 34-38). Even then, Jesus acknowledges that we won’t do it consistently, by telling Peter he’ll deny Him. Still Peter is not punished for being human. He has accepted Christ and is in relationship with Him. That is what saves Peter and the rest of us. Not the business of Heaven, but the relationship with Christ. He saves us first. Anything we do afterward is merely Him working through us and within us in that relationship. There is no need to say I am better than anyone else. I know full well I am not. In much the same way, I am not the best husband, father, son, brother (the list goes on) but those around me still love me because of the relationship I have with them.