Why Do Some believers Form Factions Despite Scripture's Warning Against Divisions and those who cause them?

Scripture clearly warns believers to avoid divisions and those who cause them. For example, Paul writes: >“Now I urge you, brethren, note those who cause divisions and offenses, contrary to the doctrine which you learned, and avoid them.” — Romans 16:17 (NKJV) Yet throughout history, we see Christians forming separate factions or denominations. A notable example is the Eastern Orthodox Church, which formally split from the Roman Catholic Church in the Great Schism of 1054 over issues including papal authority, doctrinal disputes, and cultural differences. Given this, how do Christians understand the tension between the biblical call for unity and the historical reality of denominational splits? What principles should guide believers today in maintaining unity without compromising essential doctrine?