Sung Psalm 45:9-14
Read Isaiah 57:4-10
What the Major Prophets say about harlotry in Judah:
Isaiah 1:21 speaks of moral harlotry, the faithful church becomes a harlot (as many have today)
Isaiah 23:15-18 speaks of commercial harlotry of Tyre, of even singing to attract clients. Note verse 8 and compare with Deut. 23:18 and the fulfilment in Acts 21:3 v18 speaks of the elect in Tyre.
Isaiah 57:3-9 speaks of religious and spiritual idolatry.
In Jeremiah 1 and 2 we have God married to his people (3:14, 3:1 and 2:2).
Here we see spiritual harlotry (3:6) meaning idolatry under shady trees and in high places (3:1-2). The people become like animals (2:23-24). Like a harlot they are hard-hearted and self-justifying (3:3) and casual in their work (3:9) and then we have the mention of the two whorish sisters representing both kingdoms (3:6-11). It’s well worth noting that although God divorced Israel (3:8) shortly thereafter he says he is still married to her (3:14) clearly showing that the separation of divorce does not annul the lifelong marriage bond (in God’s eyes) just as it does not today, though most believe that legal divorce is a warrant to marry again and thus commit adultery as Jesus clearly taught in Matthew 19:9