The Lutherans hold conversion resistible (the Rinteln-Marburg colloquy at Kassel)
Even so, the same theologians hold that man's conversion is free in such a way that a man can resist the Holy Spirit as he sets about the work of conversion in us, and can put an obstacle in his way; indeed sometimes a man actually does resist and obstruct. There is no efficacy of the Holy Spirit, on their view, that a man cannot by his stubbornness and defiance rob of its fruit and effect.
This is the drift of what the Rinteln theologians affirm in their colloquy with the Marburg theologians, held at Kassel by the authority of the Landgrave of Hesse. To the question 'Is the grace of conversion such that a man, by the strength of grace, can equally obey the Gospel and, through inborn malice, resist it and put an obstacle in its way?' they answered yes; the Marburg side said no.
Latin
XLII. Et tamen eo non obstante, censent iidem Theologi hominis conversionem ita liberam esse, ut homo possit Spiritui Sancto conversionis opus in nobis aggredienti resistere, & obicem ponere, imo & de facto quandoque resistat & obicem ponat: nec ullam esse Spiritus Sancti efficaciam, quam homo pertinacia & contumacia sua, fructu & effectu suo frustrari non valeat. Huc tendit quod affirmant Theologi Rintelenses in suo Colloquio cum Marpurgensibus, Cassellis authoritate Hassiae Landgravii habito. Etenim ad quaestionem illam, An Gratia conversionis ita se habeat, ut homo in virtute gratiae Evangelio obsequium praestare, & per connatam malitiam ei resistere, & obicem ponere aeque possit? Affirmative respondent, negantibus Marpurgensibus.