This was deceptive on more than one level. They had no intention of allowing Hamor to marry their sister, or becoming one people with the Shechemites. Also, they used the sacred ceremony of circumcision as though it was only an outward practice, instead of an outward sign of an inner covenant with God. Instead, Simeon and Levi used this practice as a means to incapacitate the Shechemites so that they could kill them.
Well, Levi does end up being scattered as well, with no territory of their own aside from assigned cities within the territories allotted to the other tribes. The descendants of Levi rally to Moses in the midst of the incident where Aaron made a golden calf-idol while Moses (who was busy getting the Ten Commandments from God) was absent. As a reward for their zealousness in forsaking such idolatry and fighting against those who participated in it, the tribe of Levi receive the honor of acting as caretakers of the Tent of Meeting and assisting the sons of Aaron (Moses' brother, also a Levite) in their role as priests at the tabernacle.
The honor of the priesthood was given to Aaron's descendants when Phineas (a Levite and grandson of Aaron) likewise fought against idolatry by slaying both a man and his unbelieving girlfriend who were boldly flaunting their disobedience. (Numbers 25:1-17) The Israelites had been seduced by the Moabite women and were joining them in their sacrifices to their god, namely Baal of Peor. While the Israelites were gathered in assembly to entreat the Lord's mercy, for His anger was fierce at this breaking of the covenant which Israel had made with Him -- and it seems a plague had already started breaking out -- this man Zimri (the son of a leader of a Simeonite family) brought a Midianite woman home right before the eyes of Moses and the weeping assembly. Phineas was so incensed that he took a spear and killed the couple, thus stopping the plague. For his zeal, Phineas and his descendants were awarded a perpetual priesthood.
As the Levites had no central territory of their own, but were assigned places in the territories throughout the nation of Israel, the prophecy regarding their 'scattering' was upheld, yet in a good way. Therefore, God's Word was upheld, yet individuals who followed Him with all their hearts were acknowledged and honored.
Also, you might say that Phineas' descendants were given an honor they themselves had never earned. So, regarding one's own godliness and the effect it can have on descendants, several things seem apparent:
- A person's sin can affect his/her descendants.
- A person's godliness can affect his/her descendants.
- God knows each person's heart and will punish sin and honor righteousness. (Sometimes the sinner is given additional time to repent and the righteous has to wait for his reward, but it will all be sorted out eventually) However, a man will reap what he sows.