Jesus is indeed a highly respectable prophet in Islam. And I don't see that Islam teaches quite opposite to what Jesus taught. I'll try my best to illustrate what Islam actually teaches:
1. Polygamy: There is an age-old consensus among Muslims that concludes that polygamy is permissible. The condition which Islam lays down for permitting a man to have more than one wife is that he has confidence on his part that he will be able to deal equitably with his wives in the matter of providing food, housing, clothing, and expenses, and that he will also be able to divide his time between them. Any man who doubts that he will be able to fulfill all these obligations with justice and equality would be prohibited by Allah Almighty from marrying more than one woman. Further, a Muslim is prohibited to abuse this right. For Muslims living in non-Muslim lands, polygamy may not be practiced if it is illegal in a person's country of residence. So a Muslim living in those countries has to abide by such laws and not to violate them as long as he resides in that country. In reality, Muslim men who marry more than one is a few minority. It is really hard to find one who have more than one wife, let alone four.
2. Divorce: It is the least likable permissible thing in islam. Moreover, it has conditions. Only in certaing situations divorce can be given. A man must not divorce his wife to bring harm upon his wife. Our prophet said, "Among lawful things, divorce is most hated by Allah". Divorce can be saught on such matters:
a) Physical, mental, or emotional abuse or torture.
b) Failure to fulfill the objectives and purposes for which marriage was initiated.
c) Marital infidelity.
d) Failure of the husband to provide.
Islam is not such that it only says "This is permissible & that is not:" Islam enjoined all rulings & conditions depending on situations. In reality, divorce is widespread in Western countries. Take a look at celebrities, they get divorced so many times. So they are doing just opposite to what Jesus taught them. But in Muslims, even divorce happens in certain conditions, they are not doing anything against Islamic laws. So who is right? Tell me?
3. In heaven there is no worldly rulings. It is stated that in Heaven everyone will get whatever s/he wants. Again, a good Muslim will enter Heaven & may live with his wife.
4. Jesus taught love & forgiveness. Alright. But who told Muslims believe in vengeance? In the then Arabia, the enemies always tried to hold back Islam & kill Muhammad. They were mostly idol worshippers & polytheists. They were only attacked when they attacked Muslims for no valid reason. Islam definitely has it's right to defend itself. People nowadays question that Muhammad led wars so how can islam be peacefull. But they hardly want to know who were they & what they did to Islam. Again, when Muhammad returned Mecca from Medina, the treacherous enemies were captivated & he was asked what to do with them. Prophet Muhammad said, "they are forgiven." while they deserved death punishment. This thing depends on situations. Take a look at what happened to Jesus. He is considered as son of God. But he lived only 33 years. He was killed by people. Even being a son of God he couldn't save himself, nor even God saved him. So can I ask you something? Does christianity teach way too much love & forgiveness to hide this failure? Jesus's incapability turned into forgiveness? (I hope not) (note: We Muslims don't believe him as son of God so it's different for us) In reality, look at what western powers are doing. That don't seem like love & forgiveness does that??
Anyway, I hope you read my answer carefully. Hope it helps.