From John Gill, 'A Body of Doctrinal and Practical Divinity':

We commonly say that sin is infinite, and the truest reason that can be given for it is, because God is the object of it; for as an act, it is finite, being the act of a finite creature; but with respect to the object against whom it is committed, it is infinite, and requires an infinite satisfaction; which none but an infinite person can give, and which Christ is in his divine nature, and so gave to his sufferings and death, in his human nature united to him, an infinite value and virtue, whereby justice had from them an infinite satisfaction.

Thanks be to God!