We have built up, or allowed to creep in among us, a tradition that if one is a member of the church that Jesus purchased with His own blood (Acts 20:28), we are safe.
With this idea is unconsciously implanted in many hearts a false security because they are members of His church. Also, the very dangerous belief that if a thing is taught and practiced by a certain brother, who is recognized as a great man among us, the doctrine or practice can't be wrong. "If brother says this is taught in the Bible, I believe it; he knows the Bible better than anybody I know, and he would not teach it wrongly." You have never heard anything like that?
Ephesians 5:25-27 does not teach that members of the church sanctify and cleanse or purify themselves by living such good lives. If we will study the 25th verse carefully, we shall see that Jesus Christ the Lord did this, loved the church and gave Himself for it, "THAT". "That He might sanctify and cleanse it,... That He might present it to Himself a glorious church," etc. Of course, "with the washing of water by the word," gives man's part in being cleansed and sanctified, but the power that does the cleansing and sanctifying is His blood, shed by God's grace (Eph. 1:7; Heb. 2:9) And the thing that really makes the church "holy and without blemish" is this same giving Himself for the church.
Colossians 1:21-23 states this matter clearly. What man among us, by his own goodness can be presented "holy and unblameable and unreproveable in his sight"? This is "in the body of His flesh through death," IF we "continue in the FAITH," etc. There's only one safe course: "Let God be true, but every man a liar" (Romans 3:4).