There are two types of achdut: The first is the mere concept of achdut, without really internalizing its message. This shallow achdut can lead to the hypocrisy of preaching its value, while disrespecting and maligning individuals.
The other type of achdut arises from an appreciation of the inestimable value of every Jew. Each one of us is an essential part of Hashem’s plan. We must remember what it says in Pirkei Avos, that there is no man who does not have his time. Each of us was placed upon the stage of life to deliver lines at the times when needed most.
Let us also remember that the biggest obstacle to achdut is ego. As people strive to defend their image and self-importance, this can become its own type of avodah zarah that undermines the spiritual values that they think they are fighting for. We must remember this principle: even if one deeply disagrees with the values and views of another Jew, he still can honor the tzelem Elokim that resides in each of us.
Twice a day we affirm the oneness of Hashem. This oneness is not just a statement of faith, it is a commitment to a mode of behavior that promotes oneness among us. It is divisiveness which robbed us of our Beis HaMikdash. Thus, obviously, the remedy is rising above petty differences, loving one another, and cleaving to our united purpose and destiny.
Achdut takes humility, awareness, and vigilance about our own less than perfect middos. In order to embrace all, we must have the gracefulness to embrace each.