What does the Bible say about assuming one's salvation?

In the sermon, it is noted that the greatest error someone can make is to assume they are saved without evidence of true faith. This reflects Jesus' teaching in Matthew 7:21, where not everyone who claims to know Him enters the kingdom of heaven. Assurance of salvation should not rest on presumption but on a relationship with Christ that is active, seeking, and reliant on His mercy. Believers are encouraged to seek the Lord, understanding the seriousness of their condition, which prompts a genuine pursuit of Him and His righteousness rather than self-assuredness in their status.