from the marks of special grace which accompany all true faith. The 1689 Baptist Confession affirms this clearly in chapter 14, paragraph 3:

This faith, although it be different in degrees, and may be weak or strong, yet it is in the least degree of it different in the kind or nature of it, as is all other saving grace, from the faith and common grace of temporary believers; and therefore, though it may be many times assailed and weakened, yet it gets the victory, growing up in many to the attainment of a full assurance through Christ, who is both the author and finisher of our faith.

Once more and finally, listen to the Canons of Dort:

FIFTH HEAD: ARTICLE 9. Of this preservation of the elect to salvation andof their perseverance in the faith, true believers themselves may and do obtain assurance according to the measure of their faith, whereby they surely believe that they are and ever will continue true and living members of the Church, and that they have the forgiveness of sins and life eternal.