Greetings JIMBO,
I am not answering for Stephan, but I would like to comment on your question if i might..
All men/women are endowed by God with a measure of faith. Jesus said all one needs is a mustard seed of faith. Of course that's just the beginning, because He also said IF ye continue in my word ye shall be free indeed. ( a big IF is implied). And the apostle Peter instructs us to add virtuous qualities to our faith (via good works) as we grow in the Spirit, (note: this is not growth in sanctification, but rather growth in the Spirit, because at the new birth the cup is always full/sanctified/justified no matter it's size, and remains so IF one is walking after the Spirit, and not after the flesh)...
Because the influence and consequences of sin entered into the world, God also determines ability based on capacity as well. (to whomsoever much is given much is required)..The bible says love God with all YOUR heart, and soul, not all of Paul's' heart and soul, nor all of Jesus heart and sou, but all of YOUR heart, soul, mind, and strength...This capacity varies based on many different circumstances and developments...
Along with natural endowed faith, we also have a natural endowed reasoning and conscience capabilities. Again, according to the measure given and the consequences invoked...From the light of reason and conscience "logos", we are made in His image to be logical beings, John 1-1, 1-9. (note: i might add here also that rebellious sin is not of sound reasoning faculties, therefore sin is illogical)...That being said, the bible speaks of the half-hearted and double minded, who desire part of God and in many cases most of the world, (this is the seed sown among thorns), the cares of this world chokes the faith and it becomes a half-hearted faith lacking works of sincerity and righteous motives, whereas the apostle James said faith without works is dead. If so, we can then place our God given faith in the things of this world which is all wood, hay, and stubble....This is why James told them to purify their hearts in repentance, and eradicate the double-mindedness, for one cant serve two masters...without the zeal found in 2 Cor. 7-11, one will always remain the Romans wretch with a half-hearted faith that cant be proven by deeds, trying to serve two masters...hope this helps, be blessed