One day God took Abraham outside his tent and told him, "Look towards the heavens and see if you can count the stars there. That's how many descendants you are going to have" (Genesis 15:5). At that time Abraham didn't even have one child. There are millions of stars in the sky. And it says that Abraham believed the Lord (Genesis 15:6). The word 'believe' there in the original Hebrew is 'aman' from which we get the English word 'Amen' which means 'I believe that it will be so.' So when God told Abraham that his seed would be like the stars of heaven, Abraham just said, "Amen. I believe it will be so." That's it. And it was fulfilled. Today, the children of Abraham (physically and spiritually) number in millions.
Faith means saying "Amen" when God has said something to you. Faith is always based on the word of God. "Faith comes by hearing and hearing by the word of God' (Rom.10:17). You can't have faith, if you don't listen to God. Abraham heard God first. Then he said "Amen". Nowadays, I find many believers saying that they have faith for things about which God has said nothing. They say: "I have faith that God will give me a Mercedez-Benz car. And I believe it's going to be black in colour." That's not faith. That is presumption. It is tempting God. Faith can be born only after hearing God speaking to us first. Only then can we say, "Amen. It shall be so." If you remember this, you will be saved from presumption and from "counterfeit faith".
Faith begins with God's promise and not with our desires. That which begins with our own desires will only lead to Babylon. What begins with God will lead to Jerusalem. Once God has spoken, we must keep on saying, "Amen" to it, all through our life, no matter how long God takes to fulfill His Word.. But in Genesis 16, we read that Sarah was impatient. She suggested to Abraham to have children through Hagar, her maid (Gen.16:2). What did Abraham do then? Unfortunately he said, "Amen", to Sarah too. That caused a problem for Abraham's descendants that has now lasted for 4000 years.
What are we to learn from this incident? Just this that we must never say "Amen" to man's word, when God has told us something else. God can solve any problem we have, without our having to adopt carnal methods. We don't need Sarah's advice. God is well able to do what He has promised.
Thus Ishmael was born (Genesis 15:15). Notice something here.When Ishmael was born, Abraham was 86 years old. The next verse carries on from when Abraham was 99 years old (Gen.16:16& 17:1). What happened during those 13 years? The Lord was silent. The Lord appeared to Abraham again only when he was 99, after a silence of 13 years. It is as if the Lord was saying to him, "Did you say 'Amen' to Sarah's suggestions? Then you will have to learn a painful lesson. I won't speak to you for 13 years, until you learn to value My voice more than anyone else's." Yes, God is very strict. He teaches us some lessons in a very hard way at times - for otherwise the lesson won't sink in. 13 years is a long time to live without hearing God. But Abraham learnt his lesson by then and never consulted Sarah again - not even when he was told to sacrifice Isaac much later.
God did not give up on Abraham. He now told him, "Your name will no longer be called Abram (exalted father) but your name will be Abraham (father of a multitude). You won't just have that name; you will actually be the father of a multitude." Abraham said, "Amen" once again - and within a year, he got a son - when things appeared hopeless. God gave him a son because he finally learnt to say, "Amen" to God alone. Abraham had learnt his lesson.