How do we gain our position in Christ?

Our position in Christ is gained by believing the Gospel, not by returning to the weak and beggarly elements of the Mosaic Law. Scripture says believers enjoy that position in Christ, and as a result, the righteousness of the Law is fulfilled in us who are now in Christ and have experienced salvation.

Les teaches from Galatians 4 that Paul was proving to the Gentile believers in Galatia that they were not under the Mosaic Law but under grace. The Law was weak and beggarly, yet they thought they wanted to go back under it. Paul strongly opposed this, asking why a believer would return to the Law after tasting grace. Then in Romans 8, Les explains that the righteousness or full purity of the Law, as God first gave it, was perfect, holy, and righteous. That righteousness of the Law is fulfilled in us who are believers, who have enjoyed that position in Christ, which we have gained by believing the Gospel. For those now in Christ, we have experienced salvation.

Romans 8:4

That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.

Who fulfills the righteousness of the Law, and how do they gain that position?

The righteousness of the Law is fulfilled in believers who are now in Christ. They gain this position by believing the Gospel, not by placing themselves back under the Mosaic Law. The Law was holy and righteous, but weak and beggarly for bondage, while grace is the believer's standing.