The essential problem of the left is moral and cultural relativism. Thus they seek equality for the sake of equality without consideration for morality or justice. Those that have only have because they took from those who do not have. The haves must be made to give back to those who don't have. This is the crux of the left domestic policy. Those that are strong must be oppressing those that are weak. The strong must be made weak. This is the crux of the left foreign policy.
Note that the ideology is to bring down the system rather than to actually help those who need help. Take from the rich rather than to make the poor richer. Weaken the strong rather than strengthen the weak. Currently the West (and the Israeli as pertains to the Middle East) are both prosperous and strong, thus they must be opposed with each breath.
Moral and cultural relativism is a rotten core belief yet it can perpetuate as long as there are those who have more and those who are stronger.