There is a place in the scriptures I turn to when challenged by those of the limited atonement view. It is a picture and type of what Christ would do once and for all at Calvary. In the Old Testament, Israel was instructed to observe a particular day and a statute kept ever more and still kept to this day through Christ's fulfilled sacrifice. The High Priest offered a sacrifice to the LORD on the day of Atonement or Yom Kippur for the benefit of every soul within the borders of Israel including its strangers, the faithful and yes, those unfaithful. The sacrifice, being a picture of what Christ would do, presents Israel as a type of the world with all sorts of men within itself yet only a remnant truly known of the LORD as saints. There is nothing unlimited in this atonement except its efficacy through faith. This is a lesson I can only wish our Calvinist brethren would take to heart.
"And [this] shall be a statute for ever unto you: [that] in the seventh month, on the tenth [day] of the month, ye shall afflict your souls, and do no work at all, [whether it be] one of your own country, or a stranger that sojourneth among you: For on that day shall [the priest] make an atonement for you, to cleanse you, [that] ye may be clean from all your sins before the LORD. It [shall be] a sabbath of rest unto you, and ye shall afflict your souls, by a statute for ever. And the priest, whom he shall anoint, and whom he shall consecrate to minister in the priest's office in his father's stead, shall make the atonement, and shall put on the linen clothes, [even] the holy garments: And he shall make an atonement for the holy sanctuary, and he shall make an atonement for the tabernacle of the congregation, and for the altar, and he shall make an atonement for the priests, and for all the people of the congregation. And this shall be an everlasting statute unto you, to make an atonement for the children of Israel for all their sins once a year. And he did as the LORD commanded Moses." (Le 16:29-34 AV)