I feel this is a famous saying. According to Jerry Campbell of VOA Special English, "If we can't love our neighbors who are different from us, if we can't love them for who they are, how can our country be United?"
The two clauses have the same meaning. It should be noted that like in be not like us is not a verb "like" but a preposition "like". . . The same meaning.
Jerry Campbell is the dean of Clermont Theological Seminary, which trains religious talents.
The difference between people here mainly refers to the difference of religious beliefs. Our neighbors are likely to have different beliefs from ours. In the past, people of different religious beliefs were hostile to each other and regarded each other as pagans, so they could not live in peace. Being themselves is an attribute, being true (them), (don't change yourself because of others)
After understanding, the translation is as follows:
If we can't love our neighbors with different beliefs and their true selves, how can our country be United?
PS: The last sentence, being themselves, is really difficult to translate. I hope to see a more suitable translation.