Did Abraham, David and Solomon think having many wives and concubines was sin?
There were specific instructions for the king of Israel to not acquire many wives for himself, since that could have the effect of turning his heart away from the Lord. This text predates the first king of Israel, so I would say that David and Solomon should have known that this was forbidden.
(Note: the Bible did not actually forbid them from polygamy, but from having a whole bunch of wives.)
As for Abraham specifically, aside from the affair with Hagar, he stayed married to one wife (Sarah) until she passed, after which he married Keturah and had children with her.
The Bible does not explicitly state that polygamy was forbidden, yet it would have been instructive to note that God created Adam and Eve--not Adam and Eve and Shirley and Tina and...
Having multiple wives was not a sin back then, as it is not a sin now (outside if it being illegal).
At the time of Abraham, David, Solomon, and Jesus, polygamy was part of the culture.
Even in Jesus' times, polygamy was allowed and part of the customs of the Israeli people. The historian Josephus noted that Herod was allowed to have multiple wives, because it was the custom in Israel at that time.
Furthermore, it was allowed per the Bible. When God gave the commands to Moses, he gave special instructions for the situations of multiple wives:
Had God detested polygamy, there would have been a command against polygamy. By comparison, God said that Kings shouldn't take too many wives so that his heart isn't lead astray, which is a further command showing that polygamy was allowed.
Historical and biblical evidence shows that polygamy was common practice and acceptable in the site of God and the people during the time of Abraham, David, and Solomon. Their polygamy was not a sin, just as it is not now..
As usual, my answer is long-winded, but it is, I hope, worth reading nevertheless. In answering many such questions, we need to take the long view, so to speak, and treat an important issue such as this one in the context of the entire canon of Scripture, which we today--unlike the saints of old--have the privilege of possessing in its fullness.
Probably not. The three personages you cite were all very wealthy men, and they could afford multiple wives. Keep in mind, however, all three men were responsible for the well being of each wife and was "legally" married to her for life. We need to divest ourselves today of the notion that the marriage of a wealthy man to a woman of his choosing was a trivial thing back then; it was not.
To a lesser extent, the "husband" of a concubine was also responsible for the well being of his "property," since in Old Testament times, a concubine was often a slave, as well as a "mistress" and/or a provider of children to a man whose wife (or wives!) could not have children. The "Got Questions" website is helpful in this regard.
God's design from the beginning was for a man to leave his parents, cleave to his wife (singular), and become one flesh with her. Becoming one flesh with a wife, then and now, involves more than just sexual consummation; it is an expression of physical, psychological, and spiritual intimacy. Moreover, and most significantly, from the very beginning marriage prefigured the union of Christ with his church. His bride.
As a Christian author pointed out to me recently (sorry, I can't provide the citation), the "mystery" to which Paul alludes is not that God used marriage as an analogy for Christ and the church, but that God used Christ and the church as an analogy for marriage. There is a significant difference between the two.
God's plan from eternity past was to provide a bride for His Son, so that Jesus would be the "firstborn among many brethren." God, the Father of the only begotten Son of God, could think of nothing more delightful than for His heaven to be filled with a people who would be conformed to the image of His Son (see Romans 8:28-30). One day, that people-group, comprised of every tongue and tribe and nation ("living stones," as it were) will comprise
God, then, set the standard of care of a husband for his wife very high indeed:
As for the church being Christ's bride, we need only look to the Revelation of Jesus Christ:
How is all this related to Abe, Dave, and Sol? In every way, as it turns out! Let's first switch gears.
When some Pharisees attempted to test Jesus by asking him
how did Jesus respond to them?
When the Pharisees continued their testing of Jesus by asking him
what did Jesus say?
Putting all these scriptures together, I suggest the following:
We do well to notice, moreover, that in virtually each and every instance of polygyny in the Old Testament, disputes, conflict, hard feelings, and complications of all sorts resulted. If someone reading this answer can supply an instance when multiple wives was not fraught with any of the negatives I've just cited, I'd be interested in knowing about it!
In conclusion, did Abraham et al. think their taking more than one wife was sin? Probably not. Was it God's will for them? No. Evidently, however, God was gracious in overlooking their behavior, which proceeded from their ignorance of his "good, acceptable, and perfect will" for them (Romans 12:2b). God also allowed polygyny and concubinage to exist back then out of compassion for women who were by and large held in such low esteem in male dominated cultures. I'd like to think, however, that most polygynists who were also believers in the one true God of Israel treated their multiple partners better than the unbelievers and idolaters in the nations surrounding Israel.
Today, Christians cannot plead ignorance as an excuse for taking more than one wife. Their excuse--really, a rationalization--simply will not hold water.
A final thought. If the member of a primitive tribe in the Amazon Rain Forest becomes a Christian, and he has multiple wives, how would you advise him?