This the very opposite of the Hebrew prophets’ message:

[W] hat doth the Lord require of thee, but to do justly, and to love mercy, and to walk humbly with thy God?

—Micah 6:8

In other words it is up to us, just as the secular humanists agree. This is an argument against empty ritual observance, not in favor of it.

Whether or not you accept the idea of a divine mandate for ethical behavior (I do not), you cannot maintain that the prophets leave it up to God and not to us.