(From a conversation.)
The main reason there is so much variation on such basic things as morality is because it rarely takes much intelligence at all to accept the truth – what it takes is the integrity to acknowledge what one knows is true, and that integrity is not common.
Most often people take the easy way, and simply believe whatever they hear first, or whatever they hear most often, or whatever they hear from people who make them feel good.
This makes it hard when someone actually wants to find out the one thing that is true (by definition there can only be one truth, while there can be an infinite amount of false ideas). Often they get so bogged down with false ideas that many who set out to find what is true end up falling back on the easy way, and in their frustration they accept this or that idea not because it is reasonable but for some arbitrary excuse.
When I was younger I held on to certain ideas which I knew in my heart were wrong; I focussed instead on the false and absurd arguments that were brought against the ideas I held. But, obviously, a false idea is not made true simply because a false argument is made against it.
Finally someone simply asked me if I really believed those things. I prayed and sweated for hours, and returned to the thought throughout the day, and finally saw through the excuses I had made to myself for believing the false ideas. There were a lot of people I had to ask forgiveness of, and sadly by my example of foolishness I realised that I had strengthened people in false ideas which were set in contrast to the foolishness I had believed (again, a false idea is not made true simply because it is opposed to another false idea).
God has given to everyone the ability to know and to do what is right, and this is why he justly commands us to acknowledge and do what we know is right.
Some claim of the Bible that we cannot know right from wrong without it, thinking they do honour to the Bible by saying so – but by saying so they blatantly contradict the Bible, and so do it much deeper and greater dishonour.
The Bible explicitly states (in Romans) that those who have not heard the law of God are a law unto themselves, showing the law of God written on their hearts in excusing or accusing one another, and that the hidden things of God are not only seen but plainly seen by all, so that all are without excuse who do not acknowledge the things that are true.
This is how we know the Bible is true: because God has given us the ability, and thus the responsibility, to recognise truth and to understand that it is true.
This principle which is explicitly stated in Romans is clear throughout the Bible, such as in the way the law of God is written, for example:
“The woman shall not wear that which pertaineth unto a man, neither shall a man put on a woman’s garment: for all that do so are abomination unto Yahweh thy God.” (De 22)
See that it does not say: “If someone reads this command, and understands it, and agrees that it applies to him and should be obeyed by him, but does it anyways, he has sinned, but is still a good person at heart.” No, it says “all that do so are abomination”.
All people on earth know in their hearts that it is a vile act for a person take the clothes of someone of the other gender and wear them, and they know that all the excuses made for it, that “it’s just strange”, “it’s just a joke”, “it’s just untraditional” and the rest, are all mere excuses. All people on earth who do this act do it out of the wickedness of their hearts:
“A good man out of the good treasure of his heart bringeth forth good; and an evil man out of the evil treasure of his heart bringeth forth evil: for of the abundance of the heart his mouth speaketh.” (Lk 6)
This is why “all that do so are abomination unto Yahweh”. The command was not given to “inform” us, to “impart facts”; the command was given to pronounce judgement on wickedness knowingly and willingly committed, and the command was given to justify the righteous, who already condemned such acts by their God-given conscience.
Every person on earth, whether they have seen a page of the Bible, know the Creator by his creation, and have no excuse. All can, and must, cry out: “God, be merciful to me, a sinner!” and all who so cry out “go down to their house justified” (Lk 18).
“And, behold, a certain lawyer stood up, and tempted him, saying, Master, what shall I do to inherit eternal life? He said unto him, What is written in the law? how readest thou? And he answering said, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength, and with all thy mind; and thy neighbour as thyself. And he said unto him, Thou hast answered right: this do, and thou shalt live.” (Lk 10)
This is true of any who turn to the Creator anywhere.
“Of a truth I perceive that God is no respecter of persons: but in every nation he that feareth him, and worketh righteousness, is accepted with him.” (Ac 10)
Atheists do not speak of it, or they try to explain it away, but there is evidence everywhere of people worshipping a single Creator and keeping biblical law in the midst of pagan societies without any contact with the Scripture or the people to whom Scripture was given. People know, and have turned to him out of every nation throughout all of time.
Also God testified that his law would be recognised in the eyes of every nation as wise and just, for he gave to all mankind the recognition of the truth; they only need to choose the integrity of admitting it.
“This is your wisdom and your understanding in the sight of the nations, which shall hear all these statutes, and say, Surely this great nation is a wise and understanding people. For what nation is there so great, who hath God so nigh unto them, as Yahweh our God is in all things that we call upon him for? And what nation is there so great, that hath statutes and judgments so righteous as all this law, which I set before you this day?” (De 4)