This is a question that has been asked many times by bible students young and old, and we want to get an answer to this all important question. The Bible has the answer to this question. We must search it out to learn this important truth of God. The phrase is used in Romans 8:4:

That the righteousness of the law might be fulfilled in us, who walk not according to the flesh, but according to the Spirit.

So what is it to "walk according to the spirit?" Note that walking according to the spirit is opposed to walking according the flesh. So whatever walking according to the spirit means it is not walking in conformity to flesh. Flesh and spirit are the opposite of each other here.

Spirit is that invisible force operating in us that God gives to us as a free gift.( See: Holy Spirit Defined  ) Romans 5:5:

And hope maketh not ashamed; because the love of God has been poured out into our hearts through the Holy Spirit which is given unto us.

The spirit is a free gift from God when we believe His gospel, but walking in agreement with that spirit is something that we as Christians do! God does not make us walk in agreement with his spirit. He does not force us to do it. Therefore, it is up to us, we must do it. So, again, How do we walk according to the spirit that God has given us? Romans 8:4: "That the righteousness of the law might be fulfilled in us, who walk not according to the flesh, but according to the Spirit."

Let's take a look at the context of this scripture.( context: The part or parts of something written or printed, as of Scripture, which precede or follow a text or quoted sentence ) Romans 8:5:

For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit.

Now let's take some time to look at some of the Greek words behind our English translation in this verse. In this way we get a deeper understanding of the English text. Let's look at the Greek word translated "For" in Romans 8:5.

The word is "gar." According to Strong's Greek Dictionary, the word "gar" is used for assigning a reason. What reason is Romans 8:5 assigning and to what is it assigning it? The reason is the entire verse, but what is this a reason for? Going back to Romans 8:4, "That the righteousness of the law might be fulfilled in us, who walk not according to the flesh, but according to the Spirit." Verse five is telling us the reason why the righteousness of the law is fulfilled in us who walk not according to the flesh, but according to the Spirit! Isn't that marvelous? It is because, "...they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit." They that walk according to the spirit fulfill the righteousness of the law, because they "mind" the things of the spirit. Isn't that great?

Let's take a closer look at the meaning of the Greek word translated "mind" in Romans 8:5. The word is "phroneo." According to Bullinger's: A Critical Lexicon and Concordance To The English and Greek New Testament, phroneo means: "to have mind, have intellect, to think, think out; to mind, be minded, have in mind." So, to be "spiritually minded" is to have the things of the Spirit in mind: to be thinking the thoughts of the Spirit, and to be "fleshly minded" is to have the things of the flesh in mind: to be thinking the thoughts of the flesh.

So to walk according to the spirit is to have the things of the spirit in mind, that is, to be thinking the thoughts of the spirit.