He "who does not resolve the doubt" he "instills" is a false prophet

     "We find some people who study philosophy and say some things that are not true according to the faith.  And when someone tells them that this is opposed to the faith, they answer that the Philosopher says this, but that they themselves do not maintain this; yes, that they only repeat the words of the Philosopher.  Such is a false prophet, or a false teacher, because causing doubt and not solving it is the same as giving way to it.  This is signified in Ex 21:33-34, where it says that 'if someone digs a pit and opens the cistern without covering it over,' and a cow belonging to his neighbor comes and falls into the cistern, he who left the cistern open is bound to pay him restitution.  Someone who causes doubt about these things that regard the faith, opens the cistern.  Someone who does not solve the doubt, although he has a sound and bright intellect and is not deceived, is the one who does not cover over the cistern.  Still, someone else, who does not have such a bright intellect, may well be deceived, and then the one who causes the doubt is bound to restitution, since because of him that person fell into the pit."

     St. Thomas Aquinas, Sermon 14 on the Attendite a falsis prophetis (Mt 7:15-16) 2.1.2.1 (22), 26 July 1271, trans. Mark-Robin Hoogland, C.P. (Thomas Aquinas:  the academic sermons, FCMC 11 (Washington, DC:  The Catholic University of America Press, 2010), 292).  Trans. Athanasius Sulavik:

"others, who study philosophy and advance some things which are not true according to the faith, who when told that this is repugnant to the faith, respond by saying that they themselves do not assert this, but rather they are only repeating the words of the Philosopher. Such a person is a false prophet or a false teacher, for it is the same thing to instill doubt and not to resolve it, as it is to affirm the doubt. This point is illustrated in Exodus where it says that if anyone digs a well and opens the pit and does not cover it, and if their neighbor's ox comes along and falls into the pit, the person who opened the pit is held accountable for its restitution. That person who instills doubt about those things which belong to faith opens a pit; he does not cover the pit who does not resolve the doubt, even though he himself possesses sound and clear understanding and is not deceived. Nonetheless the other person who does not possess such clear understanding is truly deceived, and so that man who instilled the doubt is held accountable for restitution, since it was through him that the other man fell into the pit."

Latin from Sulavik:

"aliqui qui student in philosophia, et dicunt aliqua quae non sunt vera secundum fidem; et cum dicitur eis quod hoc repugnat fidei, dicunt quod philosophus dicit hoc, sed ipsi non asserunt: imo solum recitant verba philosophi. Talis est falsus propheta, sive falsus doctor, quia idem est dubitationem movere et eam non solvere quod eam concedere; quod signatur in Exod. 21, 33, 34, ubi dicitur quod si aliquis foderit puteum, et aperuerit cisternam, et non cooperuerit eam, veniat bos vicini sui, et cadat in cisternam, ille qui aperuerit cisternam teneatur ad ejus restitutionem. Ille cisternam aperuit, qui dubitationem movet de his quae faciunt ad fidem. Cisternam non cooperit, qui dubitationem non solvit, etsi habeat intellectum sanum et limpidum, et non decipiatur. Alter tamen qui intellectum non habet ita limpidum bene decipitur, et ille qui dubitationem movit tenetur ad restitutionem, quia per eum ille cecidit in foveam."

Latin from Corpus Thomisticum.