The walls of the church are permeable, and this is by God's design. This means that when the church is being the church, there is no way to keep the influence of this from seeping into the world. On the flip side, when the church has lost her vision, or her focus, or they have kept both but only in the confessional documents, this means that the influence of the world will seep into the church.
Some church bodies seek to address this problem by removing the permeability of the walls. The church assumes a bunker mentality, which is just another way of saying that it has become a sect. The other response is to abandon all efforts at keeping the church functioning self-consciously as the church, and instead of seeping in, the world floods in.
When, founded by true worship of Christ, the osmotic pressure to proclaim Christ exists within the Church, she steadily influences the culture while preserving her own heart. Therefore it is critical that we press on to know Him and to love the Gospel (Hosea 6:3, Psalm 48:9, Eph. 3:14-19, Phil. 1:9-11). That pursuit is the hope of the world.