Answers
Some divisions are about real differences that matter, some are about history, language and geography, and some are about nothing at all and should shame us. The historic core is narrower than the arguments suggest: one God, Father, Son and Spirit; Christ truly God and truly man, crucified and bodily raised; salvation by grace through faith; Scripture as God's word. Hold that firmly, be charitable about the rest, and pick a local church by what it preaches and how it lives rather than by its brand.
One Lord, one faith, one baptism,
Ephesians 4:5
That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me.
John 17:21
Now this I say, that every one of you saith, I am of Paul; and I of Apollos; and I of Cephas; and I of Christ.
1 Corinthians 1:12