You're idea of destiny is skewed. We need food to survive. Whether we eat with our own hands or are fed with a spoon doesn't change that. In the same way, Christians need to serve, but not all of them will.
What do we need to serve for? I think it's a legitimate question, considering the discussion. You said we need food to survive. That is because food gives us energy, and surviving burns energy. What is happening that requires service that we wouldn't have without service?
You're simplifying predestination too much. It's not as simple as: we're born, God makes us believe, we die. Our experiences affect us just the same. The difference is that God planned our experiences from the beginning. Education and knowledge are still necessary.
Affects us how? Is it that God planned, or that God destined? Or, unlike another poster, are planning and destinying the same to you?
Even in that scenario, salvation was mutual. If a million men were hanging off a ledge and ALL were offered a hand to rescue them, but only one took the hand, then what makes that one man different? If we're all given the same choice, then the only difference between salvation and death is our choice. If it were God's power alone that saved us, then we'd all be saved. It wouldn't be an offered hand, but a forced hand.
But this isn't what's seen with free will. With it's system, our choice is what saves us. We're the ones who hold key to save ourselves.
The thing that your argument totally overlooks is that our having a pivotal role in our own salvation is not contrary to the Scriptures. The Scriptures never deny that we have a pivotal role in whether it happens or not. What they do say is that role isn't a boast-worthy one.
The Bible says, in one notorious example, "For it is by grace you have been saved, through faithand this is not from yourselves, it is the gift of God not by works, so that no one can boast. For we are Gods handiwork, created in Christ Jesus to do good works, which God prepared in advance for us to do." - Ephesians 2:8-10
You and I read this and see two totally different things, I'm sure. I'm confident you see in this predestination, and I know I see in it free will. So, the least I can do is explain to you what I see here.
"It is by grace that you have been saved, through faith" - This equates to Jesus pulling me off that ledge because I put my hand in his.
"this not from yourselves, it is a gift of God" - This equates to my not being able to pull myself off the ledge, but God offering me his hand and having the position and strength to pull me up.
"not by works, so that no one can boast" - This equates to me recognizing I couldn't get off that ledge on my own, and giving God alone the credit for saving me.
"We are God's handiwork, created in Christ Jesus to do good works" - This speaks of our design, not what ultimately happens. God designed us, created us, to do good works. That says nothing about what we end up doing.
"which God prepared in advance for us to do" - Again, this speaks of design, not outcome. God designed us, and He prepared good works for us to do. That says nothing about whether or not we do them, and there is no indication that we don't have a choice in whether or not we do them.
What do you think it means? Or, what verses do you have to support that we don't have free-will?