When our hearts are totally devoted to pleasing the Father, the good works will follow. These works come from our secret life with the Father. We are like the merchant bringing out treasure old and new. We are like the branch that is full of life from the vine and bears fruit from that life. These are the good works that bring glory to the Father. Jesus said that it was the Father in him that did the works. If Jesus relied on the Father to do good works so should we. Religion wants us to seek the approval of men whereas Jesus tells us to seek the approval of God. Religion tells us that if we set our goals, work at it and don't give up, we will be the kind of person God wants us to be. Jesus teaches us that if we will seek His will, trust in the power of His Resurrection and abide in Him, He will change us into His image.
It is a secret life because it is an inward life, an unseen life. A life spent veiled to those who are born from below. Just as men are not able to grasp the Kingdom, so they also cannot understand those who are of that Kingdom.
What the world will see is the outward manifestation of the secret life. Like looking at the light of the sun without seeing the sun itself. They behold our good deeds without seeing the source. Being secret dose not mean unknown, it simply unseen.
Even now Christ is hidden from this world. Seated at the Fathers right hand, he remains for the time being, behind the veil. Soon to be revealed to the world in all his glory with judgment and wrath to those who do not obey the Gospel; Joy and reward to those who have believed in Him. God has not left us without witness.
We have the witness of His word, His Spirit and His people. His word has been preserved across the ages as a testimony to the Gospel of Jesus. His Spirit has been convincing men of the reality of Christ. His people (Jew and gentile), have continually Born witness to God the Creator and Jesus the Lord.