See, I have chosen Bezalel son of Uri, the son of Hur, of the tribe of Judah, and I have filled him with the Spirit of God, with wisdom, with understanding, with knowledge and with all kinds of skills — to make artistic designs for work in gold, silver and bronze, to cut and set stones, to work in wood, and to engage in all kinds of crafts. Moreover, I have appointed Oholiab son of Ahisamak, of the tribe of Dan, to help him. Also I have given ability to all the skilled workers to make everything I have commanded you... - Exodus 31:2-6
I find it awesome in this passage of the scripture, the Lord himself speaking to Moses about how He had chosen men to do His work, and that He had given them the skills both technical and spiritual to do it, and that this is something that was true at that particular time of history and it remains being true even today.
Does God call out the already qualified people? Absolutely. But the greater miracle is exactly how God works his way using pieces of raw materials, like rocks, and is able to polish them into precious, valuable "objects", in a way that shows us pretty clear that it is His doing and not our own, so that people can look and see that it is He, above all and anyone else, who's in charge of "operations".
When God calls us into a ministry, it is He through the works of his Holy spirit that gives us assorted gifts by his grace (according to Ephesians 4), and everyone of them for a main purpose which is to build up, to empower the very body which we are all members of, the body of Christ that is his Church. God doesn't give us some useless gift that will go unused, or that is unneeded of, or that will go to waste.
As a matter of fact, going back to the subject of this post, God is delighted in empowering the ones He has called out. More often than not we see a lot of really good and qualified people just sitting in benches of churches while others that aren't that great nor qualified actually doing something, and by my own experience, and according to this text of Exodus, I know that God qualifies every person that willingly and open heartedly volunteers to do his part, to do a little something in return for all the blessings he/she has received, and do so with joy, giving his/her best while doing it. God then takes this not-so-great and turns into something excellent.