How can I work out my own salvation if Jesus says that I cannot do anything by myself?
The Bible tells us that we cannot save ourselves. Jesus says in John 15:5, "I am the vine, ye [are] the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing."
But then the Apostle Paul turns around and tells us that we have to work out our own salvation. He wrote in Philippians 2:12, "Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling."
They seem to be saying just the opposite things. What's going on? Why does Jesus tell us one thing and Paul tells us something different? Are they opposing each other, or are they really both saying the same thing? This can be looked at in two different ways.
First, Paul evidently had people who were expecting him to save them by talking to God for them (much like many of us expect our pastors and priests to do for us today), but Paul is telling everyone that they need to be working out their own salvation by talking to God themselves and not waiting for him (Paul) to do it for them.
Paul seems to be saying, "I love you guys, you are always trying to do the right thing, even when I am not there! But remember, you are saved by the grace of God, not by being good. You need to be talking to God about your own salvation and not depending on me to work your salvation out for you!"
Second, imagine that you are “in God's shoes”. At creation you gave people the power of choice because without choice they would be like robots. If you ever took this ability to choose away from them you would be forcing them to do what you wanted them to do, not letting them do what they wanted to do. And even if they asked you to take full control you’d still need to allow them the freedom of saying “Stop!”; the freedom to change their minds. So you decide that instead of making them robots you will send them everything needed so as to make it possible for them to do “right”, but still allowing them the right to choose a different course at any point in time. (Then if they do “right” it is because they chose to do it, not because you had forced them.) They had worked out their own salvation even though you had made it all possible.
Either way, it turns out that both Jesus and Paul are saying the same thing, they're just talking about it from two different points of view. Jesus always gives us everything we need in order to do whatever it is that He is asking us to do, but then it is up to us to do it. We work out our own salvation through the power of Christ.
An illustration might help as we try and understand this. A little boy is digging in a sandbox when he comes across a large rock. He can try to dig it out, but the rock is much to large for him. He can sit there and cry. Or he can ask his dad to come move the rock.
We are like that little boy. Sin is an obstacle that we can do nothing about, no matter how hard we try. But we CAN ask our heavenly Daddy to remove sin from our lives. (God can read our minds, and so sometimes even crying is all that we can do. And in that case it's all that is needed. He knows our hearts desires.)
Our part is asking God to help us. He will do everything else. Trust HIM !
"Nothing but his own choice can prevent any man from becoming a partaker of the promise in Christ by the gospel."