So, here's a question ... Does your belief in whether it's predestination or free-will affect how you pray for people and their salvation?
Yes, very much so.
If you are a Calvinist and you believe that God Himself sovereignly chooses whether someone should go to heaven or hell, how would you pray for that person's salvation? You'd have to pray something like, "Dear God, please choose this person to be saved. Make them believe in You. But it's up to You if they are saved or not. And if it's not Your Will, then I guess I will have to accept it."
And you'd be praying this knowing that it doesn't matter if you pray it or not. Because you can't affect God's "predetermined" plans either way. But, hooray for you, at least you are going through the motions, like a good Calvinist. Even though God Himself caused you to go through the motions, since Calvinism believes that God controls all we do.
When I pray for people's salvation, I pray things like, "Dear Heavenly Father, please put Your saving Truth in so-and-so's path. Surround them with your heavenly angels to keep evil away from them, to prevent evil from blinding them, from confusing them, from distracting them from Your truth. Help them to see the Truth, to understand it, and to realize that it's just what they need. Help them to realize what's missing in their lives, to see their need for You, to realize that there is more to life than just what they can see, that there is an eternity out there and a supernatural world. I humbly ask that, in Your mercy, You do not hand them over to the hardness of their heart, even though they have resisted You. Continue to put Your truth in their path. Make it so overwhelmingly clear that they can recognize Your efforts to reach them."
I try to pray with mankind's free-will in mind, with the fact that people have the right and responsibility to choose for themselves. (You can also pray that God brings you the opportunity to share the Gospel with them.)
I don't think it's accurate or effective to pray that God would will to save so-and-so. Because I think God does will that all people be saved. He wants all people to be saved. But He's left it up to us to respond to Him or to resist Him.
But I do think it's much more effective to pray that God provides the best circumstances possible - to get someone into a position where they can see His efforts to reach them and realize their need for Him and understand that they are responsible for their choice about Him.
I did this for a friend once, praying that God would put His truth directly in her path and give her the eyes to see it, the mind to understand it. And she told me later that she found a Christian pamphlet explaining the way to salvation ... on the floor by her feet ... in the stall of a public restroom. She became a believer soon after.
God has mysterious - and funny - ways of working sometimes.
But all this makes me wonder ... How effective are your prayers going to be if they are based on a wrong understanding of how God works?
And I also wonder ... How will the Calvinist's belief that God is the cause of everything we do (that He "controls" us and our decisions) affect their faith when they pray for something He doesn't do? When He doesn't cause a loved one to do the thing the Calvinist was praying for?
We pray that God causes someone to stop drinking or to stop taking drugs, but they keep going back to it again and again. We pray that a cheating spouse would come back to us, but they don't. We pray that God would bring back a prodigal child, but the child never returns. We pray that someone wouldn't get an abortion, but they do anyway. We pray that someone would stop mistreating us, but it just keeps going or gets worse. We pray that God would make someone believe in Him, but they remain unbelievers to the end.
If we believe that God is the cause of everything we do, then who are we going to "blame" when our prayers aren't answered? And what is going to happen to our faith in Him? How is it going to make us feel about Him? About ourselves?
Having a messed-up view of who is responsible for our choices will eventually lead to a messed-up faith. We won't be praying the way we should. We won't be putting the blame and responsibility on the right people. We won't be doing our part to obediently carry out God's Will and plans. (Because He "controls" everything anyway, right?) And our faith will suffer.
Just a thought about some of the more practical ways Calvinism hurts our faith and spiritual life. And I bet you can imagine other ways that Calvinism (the belief that God causes all the things that happened precisely as He preplanned it to be) can adversely affect our faith, our understanding of prayer and God, and how we live out the Christian life.
(For more on prayer, see my Bible Study "Prayer" post or "Prayer, Faith, and God's Will". There will be overlap between them.)