As a Christian, you are obligated to live according to the Spirit (Rom 8:12). This is because you have been given spiritual life by the Spirit (Rom 8:11). It is through Jesus and the Holy Spirit that you are justified and sanctified (1 Cor 6:11; 2 Thess 2:13). That is why you are commanded to take the ‘sword of the Spirit’, the Word, in your striving against sin and spiritual darkness (Eph 6:17). It is the Spirit, through the Word, that produces persevering faith and obedience in your life.
Romans 8:13-14 makes it clear that all true believers are being led by the Spirit. The Spirit therefore guides Christians in their life. According to that passage though, this guidance is not in the form of superficial futuristic decision making, but rather in regard to the daily mortification of fleshly desires. Galatians 5:24-25 again makes it clear that the Holy Spirit’s leading is in relation to putting off fleshly desires. The Spirit’s guidance in on par with what is written in the Scriptures (Eph 6:17) and therefore cannot ever contradict any teaching or principle in the Word. The primary source of Spirit-guidance in the life of the believer then is the Word of God which He Himself inspired for our benefit.