The 'fundamentalists' are right, and you are merely deluding yourself that this 'spirit' is of God.

The technical description for what you are propounding is 'antinomianism', and as such it's nothing new, being traceable back to the 1st century, although is more commonly associated with the Reformation, when the term was coined. At its most extreme, it argues that God forgives everybody everything, so there's no need to live in accordance with any moral standards. There is a valid expression that emphasises that the Christian is not concerned to obey the law because it is the law, but because it is the way that God has revealed as being the best.

It's hard to avoid the New Testament's strictures on specific sins: 'Let the thief no longer steal, but rather let him labor, doing honest work with his own hands, so that he may have something to share with anyone in need.' (Eph 4:28) 'But let none of you suffer as a murderer or a thief or an evildoer or as a meddler.' 1 Peter 4:15

The confusion that has arisen in the 20th century revolves around the area of sex; specifically the modern acceptance of almost anything as acceptable has led to an ever narrowing definition of 'fornication' within church circles. What is clear is how important it is in Paul's agenda: remember that when he is writing the letters to the Corinthians, it's to a church located in a pagan society where most forms of sexual indulgence were freely available. It's notable therefore that he does take a hard line: "Or do you not know that he who is joined to a prostitute becomes one body with her? For, as it is written, “The two will become one flesh.” 17 But he who is joined to the Lord becomes one spirit with him. 18 Flee from sexual immorality. Every other sin a person commits is outside the body, but the sexually immoral person sins against his own body. 19 Or do you not know that your body is a temple of the Holy Spirit within you, whom you have from God?" (1 Cor 6:16-19) The statement about sexual immorality being especially damaging because it is internal in its effect is especially striking. It's clear that there IS sexual sin; the only question is what is its boundary. However an honest assessment of the NT evidence doesn't really allow for any interpretation other than it being ALL sex outside marriage.

So how does this fit with allegations of 'Pharisaism'? Our aim as Christians is to live how God wants. What that doesn't mean is following rules because they are rules, as Galatians makes very clear; instead we are to stay in step with the Spirit. But equally in that book Paul makes a list of things that are the works of the flesh - and once again sexual immorality heads the list (Gal 5:19). It's nice to try to construct an alternative to what the bible requires - but actually it won't fly.