I read that and concluded that Calvinists believe in resistible grace. If there is any context whatsoever that grace can be resistible, then "resistible grace" as a concept is something that exists.
You need to quote what statement you're alluding to from which you derive that conclusion.
"Conclusion: the means needed to eventually convert Saul are greater than the means needed to convert the eunuch (thus preserving asymmetry of guilt and wickedness), but in each case God’s grace is sufficient to ensure the salvific outcome (thus preserving God’s irresistible grace). In short, the Bible study that proved irresistible in the eunuch’s context was resistible in Saul’s context, and so stronger means were needed (and in Saul’s case, they were graciously supplied)."The article is saying that there was a time in his life that Saul was, in fact, resisting grace. It was that time in his life after bible study, but before being struck blind.
S's resisting the grace that is sufficient for S*'s conversion doesn't entail thst S can resist the grace sufficient for S's conversion. Irresistible grace states that the grace by which God brings a dead sinner to life is irresistible for that dead sinner, not that the grace sufficient for one sinner's conversion is sufficient for all sinners' conversion.
Yes, Paul Manata has it right here. It has never been the mainstream Calvinist view that God's grace is irresistible in any and every context. That would contradict a number of Scriptures. "You always resist the Holy Spirit" (Acts 7:51; cf. Luke 7:30), etc. Rather, God's grace is never resistible *by the elect* when it comes time for God to convert them.