God wants you to be holy, so he is going to purify you if you choose to do his will. He is the one who is going to make you holy.
There are two ways God will purify us. The first is going to strip away many things you hold dear. It’s going to require active participation in his will, doing what is right and good. The second requires passive acceptance of things that are out of your control.
See everything you do and experience as a chance to grow in holiness, and God will make you into a saint.
For more on this topic check out these videos from Fr. Mike: