Acts 5:38 (KJV) And now I say unto you, Refrain from these men, and let them alone: for if this counsel or this work be of men, it will come to nought:
Earlier in this passage, Gamaliel mentioned two other men who gathered to themselves disciples. These two men perished and their disciples scattered – not to be heard from again. Jesus was crucified and his disciples grew in number. Even many of his disciples were put to death and yet the teachings of Jesus Christ continue to spread.
If it be of men, it will come to nought. If it be of God, it will (and continue to) flourish.