I'm not sure why this is a "fine line" for you, but in my view, we *always* need God's help to obey His Word. Always! Unless we're connected to the vine, we cannot bear fruit. And even those in the pagan world who follow their conscience are at least connecting, unconsciously, to God's word in order to produce something good. It's just not connecting with God in the same way Christians do, who embrace Christ's nature along with his virtue to do good.
Some Christians get confused about what God's word is, thinking it is the Scriptures primarily. But this is not even remotely true. God's word is the message God delivers directly to the hearts of men in order that they can live as God created them to live, in the image of God. So God's word is accessible by all men, even though many are not aware that it is God's word they are drawing upon when they listen to their conscience.
But it is vastly more important to embrace not just God's word to do good, but rather, the nature of God as revealed in Christ. When we embrace not just his commandments but his *nature,* we are then able to be like Christ, and not just do good deeds. We adopt his own nature, and become "born again." This is what Salvation consists of, embracing the nature of Christ so that together with him we can both do good and live in eternal fellowship with him.