Question:

What is "Spiritual Formation"? Is it scriptural?

Answer:

It's my opinion that there is no reliable answer to your question.

The PCUSA has what is called "The Office of Spiritual Formation," but I wouldn't recommend it! I also note (on Wikipedia) that a certain Dallas Willard says that "spiritual formation for the Christian basically refers to the Spirit-driven process of forming the inner world of the human self in such a way that it becomes like the inner being of Christ himself."

All I'm saying is that, like so many other things in modern America, "Spiritual Formation" ends up being whatever a sovereign individual says it is. And that is the same as saying it doesn't have a clear definition.