Your Question: Gen 11 :6 says “now nothing that they propose to do will be withheld from them” what does this mean? What does God want to say to us from this?
This chapter in Genesis is about the tower of Babel. When Noah came out of the ark, God told them, “As for you, be fruitful and increase in number; multiply on the earth and increase upon it” (Genesis 9:7). God wanted them to separate, but in Genesis 11 they did the exact opposite. They went to a plain in Shinar. They all spoke the same language and decided that they would build a city with a tower to make a name for themselves so that they would not be scattered over the face of the earth. When the Lord saw what they were doing he was really displeased with them, not only were they disobeying him, but their motives for doing so were for their own honour and glory, already they had forgotten God, and that he desires that we will honour and glorify him.
God said “if as one people, speaking the same language they have begun to do this, then nothing they plan to do will be impossible for them”. This does not mean that men are able to do absolutely everything, but there is great danger when human beings are united against God, and are arrogantly defiant in disobeying him. The punishment for mankind at that time was to have their languages confused so that they would not understand each other and have to separate.
Unfortunately in the world today, the situation of people living in isolation has largely been reversed. The world is united by being able to communicate with each other in two or three of the world’s main languages. The danger of mankind thinking that they can unite to undermine, defy, ignore or disobey God’s commandments is a growing reality. This is a warning to the world, and Christians specifically, that God will intervene ultimately, however important, clever, indestructible humans may think they are – God is in control, and will ultimately have the last word.