So, because the world is promiscuous I need to be even more promiscuous so I know how to live in the world?
That is not the life of a Christian. Rather:
The night is far spent, the day is at hand: let us therefore cast off the works of darkness, and let us put on the armour of light.
Let us walk honestly, as in the day; not in rioting and drunkenness, not in chambering and wantonness, not in strife and envying.
But put ye on the Lord Jesus Christ, and make not provision for the flesh, to fulfil the lusts thereof.
Romans 13:12-14
The term "chambering" is a euphemism - the Greek is koite, meaning sex. The term "wantonness" is elsewhere translated laschiviousness, it means to be focussed on pursuing the lusts of the body, whether sexual or otherwise. This passage directly states that a Christian life should NOT include promiscuous sex. This is pretty obvious to anyone, every church has taught it forever - it is right re-examine the teachings of the church and ensure they truly come from scripture and are not just cultural prudishness, but this one is there in black and white.
You are trying to find excuses to justify an ungodly lifestyle - trying to find ways to claim that lifestyle is not ungodly. You are doing this by being hyper-legalistic, to narrow the law down as far as possible, leaving as much outside the law as you can. But that's the attitude of a Pharisee. You are forgetting what it means to be a Christian.
We are called to be Jesus' disciples, to try and follow in his footsteps. To find the heart of God and do what He would want us to do. NOT to just avoid breaking laws, but to actually build His Kingdom on earth, bringing all things into submission to Him. And the first thing we must subjugate to Him is ourselves.
And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
Romans 12:2
And as
@Mark C constantly reminds us:
And I heard another voice from heaven, saying, Come out of her, my people, that ye be not partakers of her sins, and that ye receive not of her plagues.
Revelation 18:4