When God set his hand to deliver the Israelites from Egypt, he commanded a Passover sacrifice to be offered, and afterward, it was to be offered yearly on the fourteenth of the first month of the sacred calendar. Only those who were ritually clean were, under ordinary circumstances, permitted to partake of the Passover sacrifice.
To be ritually clean, one had to know what that meant, what measures had to be taken to meet the standard of cleanliness required. To do that implies that one had to examine his behavior, and his condition, based on certain standards.
Faithful Christians baptized into the body of Christ, having learned to keep his festivals as he commands, are also expected to examine ourselves, especially as we approach the Passover, not only at this time of year, but on a continual basis. Let me explain from the Scriptures what that means and how to go about it.