The popular saying "There's no such thing as a free lunch" probably got started in the 1930s. Economist Milton Friedman used it as the title of his 1977 book. It has applications in various other areas such as science, technology, and statistics. It is generally used to mean you can't get something for nothing. Everything has a cost that has to be payed one way or another. Sadly, today there are many people that don't understand this principle. They think everything should just be handed to them. They are oblivious to the fact that everything has to payed for somehow. For example, some think that the government has an unlimited supply of resources and can just keep doling out benefits to people with no consequences. They ignore the simple fact that there is no such thing as government money. The government is not some mystical entity with a bottomless well. The government is just other people, and government only has money it takes from the people. The government doesn't pay for anything. The people do. There is a difference between a renter and an owner of housing. A renter has no "skin in the game".
This is also true in spiritual matters. In John 6:1-14, Jesus had compassion on the multitude that was following Him because they had nothing to eat. He miraculously fed a group of about 5,000 adult men which including women and children was probably at least 20,000 (Mt 14:21). That night, Jesus crossed the Sea of Galilee, and the next day this multitude went over looking for Him. On the surface, this seems like a noble thing; but Jesus always looks deeper into the heart. "Jesus answered them and said, Verily, verily, I say unto you, Ye seek me, not because ye saw the miracles, but because ye did eat of the loaves, and were filled. Labour not for the meat which perisheth, but for that meat which endureth unto everlasting life, which the Son of man shall give unto you: for him hath God the Father sealed (Jn 6:26-27)." They were not seeking spiritual things. Rather, they were seeking a free lunch.
The book of Proverbs is an astonishing book, not only because of the wisdom it contains, but because it covers so many subjects. One of the most mentioned subjects is diligence vs, laziness. It is mentioned in 33 verses. In essence, these verses can be summarized by saying if you want something, work for it. If you're lazy, you get nothing. There is a danger in having it too easy for too long. God warned Israel that when they inherited the promised land, they would have to fight for it. He also warned them that subsequent generations that did not have to fight for it need to beware of being lost in their prosperity (Ex 34:10-16, Deut 4:9 & 23-31, Deut 11:8-25, Deut 12:28-32). The writer of Psalm 119 said, "Before I was afflicted I went astray: but now have I kept thy word (Ps 119:67)."
It is popular in some circles to teach that Biblical salvation and discipleship are given to us freely by God at no cost to us. One widely believed version of this is called Calvinism because it was taught by John Calvin. It interprets passages like Romans 10:9-10 and Ephesians 2:8-9 to mean that there are no requirements upon Christians placed by God other than a mental assent and a verbal acknowledgment. For further study on Calvinism, you can read several articles on this website as well as the book, "Faith and Works: a Bible Study on Calvinism". The doctrine of Calvinism is sometimes called "easy believism" because it basically teaches that salvation and discipleship have no requirements on the believer. All of the responsibility is on God alone.
The basis of our salvation is the blood of Jesus Christ (Mt 26:28, Rom 3:25, etc.). We cannot earn salvation because we have all sinned (Rom 3:23). God planned from before the foundation of the world to save us through manifesting Himself in the flesh, dying for our sins, and rising from the dead (Jn 17:24, Eph 1:4, 1Pet 1:20). He knew we could not do it ourselves so He did it for us (Is 59:16-17). He does not require anything from us to receive salvation other than faith in Him and obedience to the gospel (Acts 5:32, Heb 5:9). The gospel is the death, burial, and resurrection of Jesus Christ (1Cor 15:1-4). We respond to it and apply it by repenting of our sins, being baptized by immersion in the name of Jesus Christ for the remission of sins, and receiving the gift of the Holy Ghost with the initial outward evidence of speaking in an unknown language (Acts 2:38-39, Acts 8:12-17, Acts 10:43-48, Acts 19:1-6).
Some argue that saying we should do these things to receive salvation is teaching salvation by works, but we do not do anything in these steps. God does all the work. He is the One who gave Himself for us and forgives us when we repent. He is the One who washes us in His blood in baptism (Rev 1:5). He is the One who gives us the Holy Ghost. We cannot merit the free gift of salvation. That Is why God gives it by His grace. Salvation is free, but it wasn't free for Jesus. He came to earth in the flesh, humbled Himself, suffered, and died a horrible death for us. He paid the price that we could not. However, discipleship does involve works. It is not free. We must keep His commandments (Jn 14:15, 1Jn 5:3). A disciple is one who follows a teaching. If we do not follow His teachings, we are not His disciples (Lk 6:46). The root word of disciple is discipline. This involves acts of the will in obedience to the word and will of God. " Then said Jesus unto his disciples, If any man will come after me, let him deny himself, and take up his cross, and follow me (Mt 16:24)." This must be done on a daily basis (1Cor 15:31).
Everyone pays one way or the other. We can do it voluntarily and receive the benefit, or we can do it via accountability. "And whosoever shall fall on this stone shall be broken: but on whomsoever it shall fall, it will grind him to powder (Mt 21:44)." One example is tithing. We can pay tithes in faith and obedience and rely on the promises of God, or we can rob God and end up paying it and more other ways through wasting money on sin or losing it through curses (Mal 3:8-11). Everyone pays. There is no free lunch.