Interesting statement. "Illogical" how?
If they consider god one god/one person then they have no explanation for the existence of universal, invariant, abstract entities upon which logic is predicated. So, if you ask the Jew why is logic logical they should reply because God is logical. Now the process begins of examining their god. If that god isn’t triune then it fails in providing for unity and diversity. Without unity and diversity we cant even converse.
The Christian says that logic is logical because it reflects the nature and thinking of the triune God as revealed in scripture. When that God is then examined, His Trinitarian nature provides the preconditions necessary for unity and diversity which leads to understandable language, math and scientific inquiry.
Without a triune God, how do we account for unity, diversity and harmony? If he is one god/one person then where did the diversity come from? If he is many gods, then where did the unity come from? If many gods with many ideas then where did the harmony come from? The father, son and spirit are diverse yet always in agreement (unity and harmony). God has been revealed to us in Holy writ.