Sacrifices were offered in Faith of a Coming Saviour
Source: TTT
Hebrews 11:4, 17, 28
By faith Abel offered God a better sacrifice than Cain did. By faith he was commended as righteous when God gave approval to his gifts. And by faith he still speaks, even though he is dead. / By faith Abraham, when he was tested, offered up Isaac on the altar. He who had received the promises was ready to offer his one and only son, / By faith he kept the Passover and the sprinkling of blood, so that the destroyer of the firstborn would not touch Israel’s own firstborn.