Please explain the real meaning of "jealous" in the second commandment.
The Hebrew word for "jealous," as descriptive of God in the second commandment of Exodus 20, has three outstanding roots, all coming from the same original root word. The first is "purchase" or "ownership;" the second is "zeal;" and the third is "jealousy," as we ordinarily use it. The expression in this commandment is a blending of the three terms. In Zechariah 1: 14 this triple thought is exemplified: "So the angel that communed with me said unto me, Cry thou, saying, Thus saith the Lord of hosts: I am jealous for Jerusalem and for Zion with a great jealousy." Possession, zeal, and jealousy are all disclosed in the one term.
God calls Himself a "jealous" God in the larger sense of being the owner. "Thou shalt worship no other god: for the Lord, whose name is Jealous, is a jealous God." Ex. 34: 14. As Creator and Redeemer He has a right to state the laws that govern His people. If any deny this, or challenge Him, they must assume the responsibility and take the consequences. When the Saviour said, "The zeal of Thine house hath eaten Me up," He meant that it consumed Him because God, and God only, is the sole owner or possessor. Therefore He has a right to make requirements in harmony with that relationship, and no one has the right to deny that relationship, or to do anything contrary thereto.
Where the commandment says, "visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate Me; and showing mercy unto thousands of them that love Me," it is not with the ordinary meaning of human jealousy. Our God is not a jealous God in the sense of being revengeful, or because He is fearful of being encroached upon. He is not selfish or avaricious. Moses plainly said in Deuteronomy 6: 24: "The Lord commanded us to do all these statutes, to fear the Lord our God, for our good always, that He might preserve us alive, as it is at this day." We are the beneficiaries when we do what He tells us; if we do not, we receive the dire results. God, being the possessor, and the one filled with zeal for the good of mankind, has the obvious right, not merely to protect, but thus to warn.