How do we know which books should be in the Old Testament? Belgic Confession 4,6 (Pastor Winston Bosch)

Luke 11:45-52 (NIV)

45 One of the experts in the law answered him, “Teacher, when you say these things, you insult us also.”

46 Jesus replied, “And you experts in the law, woe to you, because you load people down with burdens they can hardly carry, and you yourselves will not lift one finger to help them.

47 “Woe to you, because you build tombs for the prophets, and it was your ancestors who killed them. 48 So you testify that you approve of what your ancestors did; they killed the prophets, and you build their tombs. 49 Because of this, God in his wisdom said, ‘I will send them prophets and apostles, some of whom they will kill and others they will persecute.’ 50 Therefore this generation will be held responsible for the blood of all the prophets that has been shed since the beginning of the world, 51 from the blood of Abel to the blood of Zechariah, who was killed between the altar and the sanctuary. Yes, I tell you, this generation will be held responsible for it all.

52 “Woe to you experts in the law, because you have taken away the key to knowledge. You yourselves have not entered, and you have hindered those who were entering.”