How do we know we are unable to serve God without Christ?

The struggle of humanity's incapacity to please God without divine assistance is clearly articulated in Romans 7, where Paul expresses his inner conflict between desiring to do good and repeatedly failing. He laments, 'For I know that nothing good lives in me, that is, in my sinful nature' (Romans 7:18). This inability is also echoed in Joshua 24:19, where Joshua asserts that the Israelites are not able to serve the Lord. They are confronted with their limitations and rebelliousness, which affirms that true obedience and worship require a transformation that only Christ can provide. Our efforts are frail, while Christ's perfect obedience enables us to serve God acceptably. This underscores the importance of depending on Christ for our sanctification and service to God.