We live in USA and my step son just admitted that he's an atheist, what is the best way to approach the situation ? He's is actually trying to preach and convince others to become atheist as well.
Your best course of action is just to leave him to his disbelief. It is not your responsibility to "prove" God's word to him, or to compel him to follow the straight path. After God's message has been relayed, whether or not anyone chooses to reject it is on their own soul. You can wash your hands of the matter.
If you worry that his preaching may sway you or others to his way of thinking, just read the Qur'an to learn as much about the religion as you can, and teach what you know to those who don't. Don't fall into the trap of arguing without knowledge; if you are asked to defend a position you do not know or understand, it is better to say "I don't know" than it is to (accidentally) invent a lie in God's name. If you must argue, then argue in a way that is good, with knowledge and wisdom.
Don't fear your step-son, who has rejected God's word; any evil he commits is only against himself, and only by God's leave. Don't fear your peers, who may hate you for being associated with an atheist; God knows best the truth of all matters.
Above all else, fear God.
LOGICAL CONCEPT OF GOD
My first question to the atheist will be: "What is the definition of God?" For a person to say there is no God, he should know what is the meaning of God. If I hold a book and say that ‘this is a pen’, for the opposite person to say, ‘it is not a pen’, he should know what is the definition of a pen, even if he does not know nor is able to recognise or identify the object I am holding in my hand. For him to say this is not a pen, he should at least know what a pen means. Similarly for an atheist to say ‘there is no God’, he should at least know the concept of God. His concept of God would be derived from the surroundings in which he lives. The god that a large number of people worship has got human qualities - therefore he does not believe in such a god. Similarly a Muslim too does not and should not believe in such false gods.
If a non-Muslim believes that Islam is a merciless religion with something to do with terrorism; a religion which does not give rights to women; a religion which contradicts science; in his limited sense that non-Muslim is correct to reject such Islam. The problem is he has a wrong picture of Islam. Even I reject such a false picture of Islam, but at the same time, it becomes my duty as a Muslim to present the correct picture of Islam to that non-Muslim i.e. Islam is a merciful religion, it gives equal rights to the women, it is not incompatible with logic, reason and science; if I present the correct facts about Islam, that non-Muslim may Inshallah accept Islam.
Similarly the atheist rejects the false gods and the duty of every Muslim is to present the correct concept of God which he shall Insha Allah not refuse.
(You may refer to my article, ‘Concept of God in Islam’, for more details)
QUR’AN AND MODERN SCIENCE
The methods of proving the existence of God with usage of the material provided in the ‘Concept of God in Islam’ to an atheist may satisfy some but not all.
Many atheists demand a scientific proof for the existence of God. I agree that today is the age of science and technology. Let us use scientific knowledge to kill two birds with one stone, i.e. to prove the existence of God and simultaneously prove that the Qur’an is a revelation of God.
If a new object or a machine, which no one in the world has ever seen or heard of before, is shown to an atheist or any person and then a question is asked, " Who is the first person who will be able to provide details of the mechanism of this unknown object? After little bit of thinking, he will reply, ‘the creator of that object.’ Some may say ‘the producer’ while others may say ‘the manufacturer.’ What ever answer the person gives, keep it in your mind, the answer will always be either the creator, the producer, the manufacturer or some what of the same meaning, i.e. the person who has made it or created it. Don’t grapple with words, whatever answer he gives, the meaning will be same, therefore accept it.
SCIENTIFIC FACTS MENTIONED IN THE QUR’AN: for details on this subject please refer to my book, ‘THE QUR’AN AND MODERN SCIENCE – COMPATIBLE OR INCOMPATIBLE?
THEORY OF PROBABILITY
In mathematics there is a theory known as ‘Theory of Probability’. If you have two options, out of which one is right, and one is wrong, the chances that you will chose the right one is half, i.e. one out of the two will be correct. You have 50% chances of being correct. Similarly if you toss a coin the chances that your guess will be correct is 50% (1 out of 2) i.e. 1/2. If you toss a coin the second time, the chances that you will be correct in the second toss is again 50% i.e. half. But the chances that you will be correct in both the tosses is half multiplied by half (1/2 x 1/2) which is equal to 1/4 i.e. 50% of 50% which is equal to 25%. If you toss a coin the third time, chances that you will be correct all three times is (1/2 x 1/2 x 1/2) that is 1/8 or 50% of 50% of 50% that is 12½%.
A dice has got six sides. If you throw a dice and guess any number between 1 to 6, the chances that your guess will be correct is 1/6. If you throw the dice the second time, the chances that your guess will be correct in both the throws is (1/6 x 1/6) which is equal to 1/36. If you throw the dice the third time, the chances that all your three guesses are correct is (1/6 x 1/6 x 1/6) is equal to 1/216 that is less than 0.5 %.
Let us apply this theory of probability to the Qur’an, and assume that a person has guessed all the information that is mentioned in the Qur’an which was unknown at that time. Let us discuss the probability of all the guesses being simultaneously correct.
At the time when the Qur’an was revealed, people thought the world was flat, there are several other options for the shape of the earth. It could be triangular, it could be quadrangular, pentagonal, hexagonal, heptagonal, octagonal, spherical, etc. Lets assume there are about 30 different options for the shape of the earth. The Qur’an rightly says it is spherical, if it was a guess the chances of the guess being correct is 1/30.
The light of the moon can be its own light or a reflected light. The Qur’an rightly says it is a reflected light. If it is a guess, the chances that it will be correct is 1/2 and the probability that both the guesses i.e the earth is spherical and the light of the moon is reflected light is 1/30 x 1/2 = 1/60.
Further, the Qur’an also mentions every living thing is made of water. Every living thing can be made up of either wood, stone, copper, aluminum, steel, silver, gold, oxygen, nitrogen, hydrogen, oil, water, cement, concrete, etc. The options are say about 10,000. The Qur’an rightly says that everything is made up of water. If it is a guess, the chances that it will be correct is 1/10,000 and the probability of all the three guesses i.e. the earth is spherical, light of moon is reflected light and everything is created from water being correct is 1/30 x 1/2 x 1/10,000 = 1/60,000 which is equal to about .0017%.
The Qur’an speaks about hundreds of things that were not known to men at the time of its revelation. Only in three options the result is .0017%. I leave it upto you, to work out the probability if all the hundreds of the unknown facts were guesses, the chances of all of them being correct guesses simultaneously and there being not a single wrong guess. It is beyond human capacity to make all correct guesses without a single mistake, which itself is sufficient to prove to a logical person that the origin of the Qur’an is Divine.
CREATOR IS THE AUTHOR OF THE QUR’AN
The only logical answer to the question as to who could have mentioned all these scientific facts 1400 years ago before they were discovered, is exactly the same answer initially given by the atheist or any person, to the question who will be the first person who will be able to tell the mechanism of the unknown object. It is the ‘CREATOR’, the producer, the Manufacturer of the whole universe and its contents. In the English language He is ‘God’, or more appropriate in the Arabic language, ‘ALLAH’.
QUR’AN IS A BOOK OF SIGNS AND NOT SCIENCE
Let me remind you that the Qur’an is not a book of Science, ‘S-C-I-E-N-C-E’ but a book of Signs ‘S-I-G-N-S’ i.e. a book of ayaats. The Qur’an contains more than 6,000 ayaats, i.e. ‘signs’, out of which more than a thousand speak about Science. I am not trying to prove that the Qur’an is the word of God using scientific knowledge as a yard stick because any yardstick is supposed to be more superior than what is being checked or verified. For us Muslims the Qur’an is the Furqan i.e. criteria to judge right from wrong and the ultimate yardstick which is more superior to scientific knowledge.
But for an educated man who is an atheist, scientific knowledge is the ultimate test which he believes in. We do know that science many a times takes ‘U’ turns, therefore I have restricted the examples only to scientific facts which have sufficient proof and evidence and not scientific theories based on assumptions. Using the ultimate yardstick of the atheist, I am trying to prove to him that the Qur’an is the word of God and it contains the scientific knowledge which is his yardstick which was discovered recently, while the Qur’an was revealed 1400 year ago. At the end of the discussion, we both come to the same conclusion that God though superior to science, is not incompatible with it.
SCIENCE IS ELIMINATING MODELS OF GOD BUT NOT GOD
Francis Bacon, the famous philosopher, has rightly said that a little knowledge of science makes man an atheist, but an in-depth study of science makes him a believer in God. Scientists today are eliminating models of God, but they are not eliminating God. If you translate this into Arabic, it is La illaha illal la, There is no god, (god with a small ‘g’ that is fake god) but God (with a capital ‘G’).
"Soon We will show them our signs in the (farthest) regions (of the earth), and in their own souls, until it becomes manifest to them that this is the Truth. Is it not enough that thy Lord doth witness all things?"