Nadab and Abihu offered up incense to the Lord by way of a “strange fire.” The Lord does not allow anything “strange” to approach Him. He had only one authorized ignition source in the entire tabernacle system: the fire on the altar of burnt offering. This fire had been lit by the Lord Himself on the inaugural day of the tabernacle. “Fire from heaven” is the biblical term. We call it a lightning.
After bringing us into covenant with Him by cleansing us with His blood, the Lord leads us to a life of consecration. The longer we walk with the Lord, the more He challenges us to let go of the world. Activities we enjoyed without guilt in the past now become restricted by convictions. But with each conviction followed comes a new liberty to serve the Lord in consecrated holiness.