Frankly, this post is not helpful, because surprisingly few people these days feel called to discern a vocation, and the Scripture you provide does not actually support your specific claim, that being that someone entirely using their natural abilities and education to serve God in an outwardly impressive manner is both possible and also risks damnation.
I would assert that, rather, it is impossible to even desire to serve Christ our true God at all without a calling from the Holy Spirit, and if one is able to discern the specific vocation He has in mind for us, this is sufficient, and furthermore, while in ministry as in all things our salvation and our ability to save others is aided by the grace of God the Holy Spirit, the specific vocations we are suited for are dependent on those natural abilities and education that we have been blessed with, according to the will of our Almighty and most merciful God, so that, for example, a heroic local Presbyterian lady I know who runs a homeless shelter and is the chief chaplain for the county fire department (and consequently handles situations where the fire brigade needs a chaplain, for example, assisting the relatives of someone found unresponsive who the paramedics determined had died, or providing pastoral care to firefighters who have come across a gruesome scene, such as a child killed in a traffic accident), has very specific strengths that I lack, along with stupendous health, particularly considering she is in her mid seventies.
We are called by our Heavenly Father to offer the best of ourselves to Him, and in doing so we will be aided by God the Holy Spirit, for as Christ our God has taught us, to whom much is given much will be expected.