Without Me, you can do nothing. (John 15:5)
The Cross simply says that an order, though it be religious, well-motivated, or good-intentioned, but nevertheless proceeding from man in his natural state (not necessarily in defiance of God or in conscious rebellion against Him, but just the expression of man's natural state as he is), the Cross says that this entire order is set aside. God has judicially judged it and put a ban upon it. In the Cross of the Lord Jesus God has said finally: 'You in your natural state cannot serve Me, and cannot bear any fruit to My glory! It is possible to go out and work, labor, and die of the strain of trying to serve Me and yet it still remains true that you cannot, out from yourself, by any natural resources whatever, bear fruit unto Me.' The only thing that can ever get through to God's end, and that can be in Life – eternal, Divine, heavenly Life – is that which proceeds from the Holy Spirit.
How sweeping that is! How that analyzes and dissects everything! Of the things we say, for example, it continually presents the interrogation: 'Was that spoken in the Holy Spirit?' It is not enough to ask ourselves: 'Did I mean it well? Did I intend it for the Lord?' but: 'Was it said, was it done, in the Holy Spirit, or did I do it?' It is not a question of motive or of intention, but of the source from which we did it. We have daily to recognize that our lives must be subject to the Holy Spirit, and when we are aware that there has been something of our own will, we have to be faithful before God about it.
By T. Austin-Sparks from: The Battle For Life - Chapter 3