3. Tithes were given to the Levites and priests, but there are no Levites and priests in the new covenant. 

Levites and priests were tied to the sacrificial system of the old covenant. Now all believers are priests (1 Pet. 2:9; Rev. 1:6; 5:10; 20:6), with Jesus as our Melchizedekian high priest (Heb. 7).