Re-posted to edit an error, "of the faith" should read "in the faith."
The Saints perseverance is because of God's preservation. So as we examine our lives, to see if we are "in the faith" we will find our efforts to follow Christ on His paths of righteousness. But what if we do not? Then we should question our salvation, because as a person whose faith is protected by the power of God, our commitment to Christ as our Lord should be manifested as a core attribute. See 2 Corinthians 13:5.
One of the evidences of an indwelt Spirit is that our conscience convicts us when we stray for Christ.