…that I may gain Christ and may be found in Him, not having a righteousness of my own derived from the Law, but that which is through faith in Christ, the righteousness which comes from God on the basis of faith
– Philippians 3:8b-9
It is not for anyone but God to say whether or not we are found in Christ. This righteousness that enables us to be found in Christ is not something before men but before God. It is not even we ourselves who determine it; God is the One who determines it. The way He determines this is by whether or not we have faith in Christ.
Adapted from Philippians: That I May Gain Christ by Titus Chu, page 191