Doctrine has an influence upon practice

"Doctrine has an influence upon practice, especially evangelical doctrine, spiritually understood, affectionately embraced, and powerfully and feelingly experienced; so true is what the Apostle asserts, that the Grace of God, that is, the Doctrine of the Grace of God, that bringeth Salvation, the good news, the glad tidings of salvation by Christ, which is peculiar to Gospel Doctrine, hath appeared to all men, Gentiles as well as Jews, in the external ministry of the word; teaching us, to whom it comes with power and efficacy in the demonstration of the Spirit, that denying ungodliness and worldly lust, we should live soberly, righteously, and godly in this present world, Tit. ii. 11, 12." - John Gill, Introduction to the Body of Divinity, Pg. xxiii


I like what he says here. Doctrine has an influence upon practice. Of course we know that we may believe the truth and yet sometimes what is believed does not right away translate in what we practice. But the order is first doctrine and then practice. Not that we look to doctrine first and then second to our practice but rather it is the case that as we look to doctrine always that it SHOULD turn out to practice.