There is no evidence to point to any spiritual significance to the fact that seven sins are mentioned, and not six or eight. Neither are the sins mentioned of any special significance. These are likely the sins that were prominent in Malachi’s day. The fact that he lists as many sins as he does points to Israel’s state of deformation, and how worthy Israel is to be punished by God when He comes. The sins that are mentioned are sins against both the first and the second tables of God’s law, that is, sins committed against God and against one’s neighbour. Some of the sins are abominations in the Lord’s sight; that is, they are detestable, odious.
5 “Then I will draw near to you for judgment. I will be a swift witness against the sorcerers, against the adulterers, against those who swear falsely, against those who oppress the hired worker in his wages, the widow and the fatherless, against those who thrust aside the sojourner, and do not fear me, says the LORD of hosts.