The Solid Declaration condemns the synergists
The Book of Concord also contains the Solid Declaration, a fuller restatement of those articles, and there they condemn the synergists' doctrine. The synergists picture man in spiritual matters as not altogether dead to good, merely badly hurt and half dead.
They grant that free choice is too feeble to start, to turn itself to God by its own strength, or to obey God's law wholeheartedly. But once the Holy Spirit starts the work, summoning us by the Gospel and holding out his grace, forgiveness of sins and eternal salvation, free choice (they say) can go out to meet God with its own natural powers.
On this view it can contribute something to its own conversion, at least a little and weakly. It can assist and cooperate, ready and apply itself to grace, lay hold of it, embrace it and believe the Gospel. And as the work is continued and kept up, it can work alongside the Holy Spirit with its own powers. (Article 2, rejected errors, no. 4.)
Latin
XX. Et in solida eorundem articulorum declaratione & repetitione, quae in eodem libro Concordiae inserta est, damnant dogma synergistarum. Qui fingunt hominem in rebus spiritualibus non prorsus ad bonum esse mortuum, sed tantum graviter vulneratum & semimortuum esse. Et quamvis liberum arbitrium infirmius sit, quam ut initium facere, & seipsum propriis viribus ad Deum convertere, & legi Dei toto corde obedire possit: tamen si Spiritus Sanctus initium faciat, & nos per Evangelium vocet, gratiam suam, remissionem peccatorum, & aeternam salutem nobis offerat, tunc liberum arbitrium propriis suis naturalibus viribus Deo occurrere, & aliquo modo (aliquid saltem, etsi parum & languide) ad conversionem suam conferre, eam adjuvare, cooperari, sese ad gratiam praeparare & applicare, eam apprehendere, amplecti, Evangelio credere, & quidem in continuatione & conservatione hujus operis, propriis suis viribus, una cum Spiritu Sancto cooperari posse. Art. 2. in rejectione errorum num. 4.