One could argue that the reconciliation process requires works, and to a degree this is true. But, it is not within the mortal capacity to achieve complete reconciliation to God apart from His assitance as a result of the Fall. So the undeserved and unmerited gift of Grace is necessarily invoked. Wherefore, my soul delighteth to prophesy concerning him, for I have seen his day, and my heart doth magnify his holy name. Similar to Paul's usages, this statement is relatively ambiguous when taken out of context.
Faith is the only requirement for salvation implicated here.
Similar to statements made by Paul. Works could not be implicated to any significant degree as very little time had elapsed between the delivery of his address which brought about the faith and change in their hearts and this pronouncement. Thus, Grace only by faith is once again implied. And it shall come to pass that whosoever shall believe on the Son of God, the same shall have everlasting life. This passage states that only believing is necessary to obtain eternal life.