Colossians 2:17

Which are a shadow of things to come; but the body is of Christ.

The Old Testament feasts were only a shadow — Christ is the substance.

The Shadow Day of Atonement

Only once a year, the high priest would go through the veil to the mercy seat with the blood which he had shed of the sin offering.

Leviticus 16:15

Then shall he kill the goat of the sin offering, that is for the people, and bring his blood within the vail, and do with that blood as he did with the blood of the bullock, and sprinkle it upon the mercy seat, and before the mercy seat:

The veil remained, and no one else could enter.

The Real Day of Atonement

Only once for ever, the Lord Jesus Christ tore through the veil when He shed His own blood, the perfect sin offering.

Matthew 27:51

And, behold, the veil of the temple was rent in twain from the top to the bottom….

Any believer can boldly approach the Heavenly Mercy Seat.

Hebrews 4:16

Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need.