A Sinner in the Church?

Dietrich Bonhoeffer said in Life Together, "For the pious community permits no one to be a sinner. Hence all have to conceal their sins from themselves and from the community. We are not allowed to be sinners. Many Christians would be unimaginably horrified if a real sinner were suddenly to turn up among the pious. So we remain alone with our sin, trapped in lies and hypocrisy, for we are in fact sinners."