Leviticus 17:7
And they shall no more offer their sacrifices unto devils, after whom they have gone a whoring. This shall be a statute for ever unto them throughout their generations. And they shall no more offer their sacrifices unto devils, after whom they have gone a whoring. This shall be a statute for ever unto them throughout their generations.
God positively commanded Israel to offer no sacrifice except at the door of the tabernacle at Shiloh. To erect another altar for sacrifice and worship was rebellion against the Lord and a departing from God. Such a separate altar would lead the people away from the true faith into idolatry.
Disobedience to this statute would bring the wrath of God upon the whole nation, not upon the guilty alone. Therefore those who felt they could not abide without an altar of their own were to leave their land and come share the possessions and privileges of their brethren rather than transgress.