The following is a quote by a leading atheist in the 19th century. You may have heard something like it.
'The visiting on Adam’s descendants through hundreds of generations dreadful penalties for a small transgression which they did not commit; the damning of all men who do not avail themselves of an alleged mode of obtaining forgiveness, which most men have never heard of; and the effecting a reconciliation by sacrificing a son who was perfectly innocent, to satisfy the assumed necessity for a propitiatory victim; are modes of action which, ascribed to a human ruler, would call forth expressions of abhorrence; and the ascription of them to the Ultimate Cause of things, even not felt to be full of difficulties, must become impossible.' (This Atheist is being quoted by George MacDonald in his sermon "The Truth in Jesus." The name of the man is not known. http://www.ccel.org/ccel/macdonald/unspoken2.xiii.html)
If you are attracted to Jesus yet you are bothered when you hear something like that—because it certainly does make God seem unjust—then you might appreciate what many early Christians believed. (If the early Christians were right, the payment was figurativie in nature; it is what it cost God, to get people to trust Him.)
You might also appreciate the sermon Justice.
What's Wrong with the Innocent Dying for the Guilty?