The children of Israel were to keep themselves separated from the other nations but, by intermarrying with the different nations around them, they had compromised and taken on their abominations. The answer for them, though it might seem harsh, was to separate from their heathen marriages.
The message of Haggai, chapter two, is a message of coming glory (see Haggai 2:3, 7, 9; compare 1:8). The importance of the message is shown in the time in which it was given.
Evidently, at least in the past, there was a creature in the oceans called leviathan. However, as you study the description in Job 41, you will see that it does not match any known creature today.
As God continues to confront Job with His greatness, Job makes his first feeble answer: “Behold, I am vile; what shall I answer thee” (verse 4)? God then asks Job if he has the abilities and powers of God. God closes this chapter with a description of behemoth as the chief of the ways of God.
The purpose of this passage is to show Job the greatness of God in caring for all the beasts and the inability of Job to begin to grasp the required knowledge and wisdom for this care.
