What does Galatians 5:1 tell Christians to stand fast in?

Galatians 5:1 admonishes believers to stand fast and unmovable in the liberty—the freedom—by which Christ has made them free. It further warns them not to be entangled again with a yoke of bondage. In the surrounding context, that bondage is identified as the Law, a legal yoke.

Les teaches that Galatians 5:1 is an admonition to stand fast and unmovable in the liberty, the freedom, wherewith Christ hath made us free. He stresses that believers are not under bondage but have liberty and have been set free, and they should not be entangled again with that yoke of bondage. Les explains that this yoke of bondage is the Law, which was a legal yoke of bondage. He connects Judaism, the religion of Christ's day and largely Orthodox Jewry today, back to the pure Mosaic and Levitical Law from Moses' time.

Galatians 5:1

Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage.

Why did Paul tell the Galatian believers to stand fast in the liberty in Galatians 5:1?

Paul warned the Galatian believers because legalizers were infiltrating the congregations he had established in Asia Minor, trying to entangle them again with the yoke of bondage—legalism, the law, and Judaism. Christ had made them free; depending on flesh-works like circumcision for salvation would cancel the cross and profit them nothing.