unite in (someone or something)
1. To join or combine (with someone or something) in some particular task, action, or event. Despite our differences, our two countries have united in the war against terror. The various companies announced that they are all united in their opposition to the proposed legislation.
2. To join two or more people or groups together in some union or partnership. In this usage, a noun or pronoun is used between "unite" and "against." I just believe a priest must be the one to unite you in marriage—to me, it isn't marriage if religion isn't a factor in it.. The goal of the charity event its to unite people in a wonderful cause.
unite someone in something
to join two or more people in something, usually marriage. The preacher united the couple in matrimony. A judge united them in marriage.
unite in something
to come together in something. Let us unite in our efforts. We will unite in song.