Yet Jesus did teach this, as have all master teachers. So Christianity does teach it (and often ignores it.) There is a reason for this - it is the truth.

I view your understanding of religions as shallow. For one, you seem to lack the ability to discern the core, original teaching, from layers later added by politicians.

This is not unusual and I am not putting you down. It is hard to discern until you have your own spiritual experience. Then, the teachings make sense, and the genuine core of them stands out. This is not something I can impart to you. But I believe when you arrive there, you will see the dissimilarities as shallow, and the similarities at the core.