God: "I looked for someone to take a stand for me, and stand in the gap" (Ezekiel 22:30)
God’s commands are not arbitrary. They are grounded in His moral character, what He is like within Himself, and orientated towards His purposes for His creation.
No church is healthy enough to resist contamination from persistent sin in its midst, any more than the healthiest and most nutritious bushel of apples can withstand contamination from even a single bad one. The only solution in both cases is separation.