I have never had any doubt about the power of unity.
What you can do alone is nothing compared to what you can do working with others in a team.
The English say two heads are better than one; and unity is strength.
Do not go alone when there are people you can go with.
The more people you have on your side, the stronger you are.
What the world needs is to come together not to tear apart. The fact that the Berlin Wall came down is big testimony of the importance of coming together instead of staying apart.
We have organizations like African Union, European Union, United Nations.
The United States of America is a federation of states. Each of them is strong enough to stand on its own; but stronger as part of a whole.
There really can be no doubt that unity is strength. Accepted or rejected, this is a fact.
But unity may become weakness instead of strength if it is mismanaged. Injustice and other evil practices can mar unity and rob it of its strength.
Hence, we say that unity is strength depending on how it is managed.
Always make unity a source of strength not a source of weakness by how you manage it.