When a believer enters by faith through the door, he is safe and secure, because he immediately comes face to face with the altar.  This is God's provision in the blood for all the sins of mankind.  The altar of burnt offering stood just inside the door of the tabernacle.  It was in the shape of a square, seven and a half feet by seven and a half feet, and four and a half feet high.  It was large enough to hold the biggest sacrificial, substitutionary animal to be sacrificed.  It was built of wood, overlaid with brass.  The wood speaks of the body of Jesus; the brass speaks of the judgment of God on our sins; the fire of the wrath of God which was spent on our Savior Jesus.

But the wood was not destroyed because it was encased in the brass.  It was sealed in, air tight, by the surrounding brass.  This is a wonderful picture of the incorruptibility of the body of Jesus, our Lord.  Subjected to the intense heat of the wrath of God on our sin, He was able to withstand it all, and to rise again from the dead.

But even though subjected to this intense heat of the wrath of Almighty God, He was not destroyed, but was able to say concerning His life:  No one takes it from me, but I lay it down of my own accord.  I have authority to lay it down and authority to take it up again.  (John 10:18)

The fire on this altar was kindled from heaven.  It fell from God and kindled the sacrifice when the tabernacle was completed and dedicated.  No human hands brought the kindling fire, no man-made fire burned on this altar:  Fire came out from the presence of the Lord and consumed the burnt offering and the fat portions on the altar.  And when all the people saw it, they shouted for joy and fell face down (Leviticus 9:24).

It's important to notice that this fire fell from heaven and was not kindled by human hands.  Salvation is entirely and exclusively of the Lord.  No human effort, no human help, no human contribution was made to kindle the fire on this altar.  It has to be all by the grace of God, apart from all human help and merit, religion and works.  To do it any other way meant certain death.  The two sons of Aaron, Nadab and Abihu, in Leviticus 10, brought strange fire and were stuck dead by the fire which fell upon them from heaven.

The fire on this altar of burnt offering was kindled once and for all, and was never allowed to go out and it was never to be repeated:  The fire on the altar must be kept burning: it must not go out.....The fire must be kept burning on the altar continuously; it must not go out (Leviticus 6:12,13).

It would burn continually, always ready for the sinner who came.  This speaks of the fact that the sacrifice always stands to plead for the saint who has come by way of the Cross.  There is no waiting and no doubting.  The fire was kindled as a perpetual testimony of the finished work of Jesus.  His sacrifice was once and for all, never to be repeated.