The problem is this:

Ubaldus made an algebraic mistake.

In lines 2 and 3, he included 3 +1's and 3 -1's. All's fine and well and everything equals zero. In line 4, there are 4 +1's and 3 -1's.

You can't add a term to one side without adding it to another

In essence, Ubaldus added 1 to the right side without completing the same operation on the left He may have been dealing with infinite series, but zero is zero anyway you slice it, even if you're talking about a billion terms of (1-1). The number of terms does not affect the outcome of the operation, until a person erroneously adds a 1 without adding a -1. Of course this will make falsely suggest 0 = 1. Had this worked out, I am not sure it proves there is a God anyway..