The church is failing in the current day because it disbelieves Jesus. The liberal church believes Jesus' command to care for the poor and seek justice, but disbelieves Jesus' warning that the only way to the Father is through faith in himself. The Conservative church believes in the cross, but by and large in practice rejects Jesus' teaching on the poor and social justice.
The church in the current day finds the teachings of Jesus to be too radical or too inconvenient. We want Jesus in our way and often that is why we find that Jesus is no where near in the church.
The church struggles because it wants an easy religion. And this watered down religion offers little to the world. It is an inconvenient religion which fully grasps the teachings of Jesus on the need for salvation, care for the poor, and concern for justice for all that is a religion that will attract followers.
The early church did not grow so quickly because faith was convenient, but because faith was radically beautiful. Convenience is not the friend of true religion but the enemy.