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Pergunta: Como é que Lehi, um não-levita, realizar sacrifícios?
Question: How could Lehi, a non-Levite, perform sacrifices?
In the Bible there are instances where men from non-Levite lineage offered sacrifices
One example that comes to mind is that of Gideon, a judge of Israel, who, like Lehi, was from the Josephite tribe of Manasseh. Commanded of God to build an altar, Gideon made an acceptable burnt offering to the Lord, and was in no way condemned for his action (See Jud. 6:24-26). The prophet Samuel was from the Josephite tribe of Ephraim, yet he too offered sacrifices (1 Sam. 1:1; 1 Sam. 7:9-10; 1 Sam. 10:8; 1 Sam. 13:15). The general consensus among Bible scholars is that the idea that only descendants of Aaron could offer sacrifices was a late (post-exilic) concept in ancient Israel. It led to such anomalies as the later chroniclers assigning Samuel to the tribe of Levi in 1 Chron. 6:33-38 to justify his having offered sacrifices. It is interesting that the first sacrifice offered for the Israelites after they left Egypt was performed not by a Levite, but by Jethro, the father-in-law of Moses, a non-Israelite (Ex. 18:12). 
- This answer is based on a FAQ from the FARMS/Maxwell Institute website (accessed 19 December 2007); it may have been altered by FAIR wiki editors. off-site