There is a sense in which all believers in Jesus Christ are "set apart". It's the same as the words "made holy" or "sanctified". And it's true of all believers that they are "set apart" from the world and unto God when they become a Christian. That's what "Saint" means. (Contrary to the unbiblical teaching that a "saint" is some ultra-special miracle-producing high-end Christian who needs to be "canonized" to be a saint.)
When we come to Christ, we are Saints. That's why Paul the Apostle addresses his letters to "the saints at..." whatever church he's writing to.
But did you know you are "set apart" even beyond that?
Listen to Paul in the Letter of Paul to the Galatians, Chapter 1, Verses 15,16:
"But when God, who had SET ME APART even from my mother's womb and called me through his grace, was pleased to reveal His Son in me so that I might preach Him among the Gentiles."
See, God had a plan for Paul. And He set Paul apart from his mother's womb!
No surprises for God. God is sovereign, and has planned (decreed) the end from the beginning. Paul didn't one day think, "I'm gonna be an apostle and a preacher", and God say, "Wow! I was hoping you'd do that!" No. He set Paul apart from his mother's womb.
Now listen here...
Do you think God is surprised at your life, Christian? Wouldn't that be ridiculous?
No, God has set you apart from YOUR mother's womb, too. I don't know for what. You might be a famous Bible teacher or preacher. Or you might be an unknown housewife or a businessman or a mommy or daddy or waitress or soldier.
But you are set apart for something. In fact you are set apart for LOTS of things, over the years. Your "something" may change from time to time. God has set you apart for that.
You may fail at things. Let me rephrase that -- you WILL fail at things. You may be confused at times on what you are set apart for.
Doesn't matter. You are set apart by God. From your mother's womb.
It could be one tiny word of caring that you utter, which helps someone else get through their day, so they can do what they were set apart for. It could be your sharing the gospel with your children, or a co-worker. It could be lifting up your spouse or family member or someone else, in prayer. If so, you were set apart for that. From your mother's womb.
Watch him work in your life in a thousand ways, and you will see (sometimes only looking back) what you were set apart for.
And you know what? He will be glorified in that.