In an effort to try to justify the use of mechanical instruments of music in worship, some say that their use is not a doctrinal issue. God has spoken in the New Testament that singing is the kind of music we must use if we expect to worship Him in spirit and in truth. Singing is the limit of God’s command. Some may say, "The Bible does not say not to use mechanical instruments of music in worship." When God gives a command to do something, He does not have to say, but don’t do this, and don’t do this, etc.
People today may think that it makes no difference if they add mechanical instruments of music in worshipping God. In the Old Testament we have the example of Nadab and Abihu who were also presumptuous in their thinking that it made no difference. In Leviticus 10:1-2 (NIV) we read, "Aaron’s sons, Nadab and Abihu, took their censers, put fire in them and added incense; and they offered unauthorized fire before the Lord, contrary to His command. So fire came out from the presence of the Lord and consumed them and they died before the Lord."
In Leviticus 16:12-13 God commanded, "Then he shall take a censer full of burning coals of fire from the altar" of burnt offering to burn the incense in the tabernacle. But Nadab and Abihu decided to do it their own way and get the coals of fire somewhere else. They offered unauthorized fire. They died a horrible death because they did something God did not authorize. Just as Nadab and Abihu offered unauthorized fire, is there any excuse for people to offer unauthorized mechanical instrumental music to the Lord?
The use of mechanical instruments of music in worship does make a difference, because God has never permitted man to devise the plan or means for his worship of God. This is very serious, because we will lose our souls through presumptuous sins just as Nadab and Abihu lost their lives through their presumptuous sins. Judgment Day will be too late to find out that it is wrong to use unauthorized mechanical instruments of music to worship God.