I have heard this several times. It sounds good even to me and if properly understood it is true but it is rarely understood. It is interpreted to mean “All we need to do is to keep going as we are.” That is dangerous, a false lie, it is the modern equivalent of the servant who was given one talent and chose to bury it in the ground.
The key word is Faithful. Most people associate faithfulness with things staying the same, with remaining as we are, with keeping the status quo. However faithfulness is one of relationship, it is not faithful to suggest inside a relationship that both people must remain the same to keep things as they are, there must in any relationship be space to grow and change. Indeed faithfulness is altering a relationship to accept the change in another. What would we think of mother who kept her baby in nappies as that was a way to faithful or insisted in carrying the child everywhere no matter how big they grew. I think we would feel that such a person was psychologically in trouble. We know in our relationships with other people that being faithful is actually a matter of continual change.
So it is with God, the call for the church to be faithful is not a call for the church to be static but a call for the church to adapt its relationship to God as its circumstances and understandings of God change. Fighting to keep things the same because that is being faithful, is a failure of relationship, and far from being faithful it is highly unfaithful.