Exodus 22:29b and 30 say, “The firstborn of thy sons shalt thou give unto me. Likewise shalt thou do with thine oxen, and with thy sheep: seven days it shall be with his dam; on the eighth day thou shalt give it me.” Here we see that the firstborn both of men and of cattle were to be given to God. According to Exodus 13, the reason for this was that the firstborn among the children of Israel were redeemed at the Passover. Exodus 13:2 says, “Sanctify unto me all the firstborn, whatsoever openeth the womb among the children of Israel, both of man and of beast: it is mine.” According to verse 15, an Israelite was to explain to his son, “And it came to pass, when Pharaoh would hardly let us go, that Jehovah slew all the firstborn in the land of Egypt, both the firstborn of man, and the firstborn of beast: therefore I sacrifice to Jehovah all that openeth the womb, being males; but all the firstborn of my children I redeem” (lit.). Therefore, giving the firstborn to God is related to the redemption of the firstborn at the time of the Passover.
All the descendants of Adam, the first man, are regarded as firstborn ones. In Adam, we all are the firstborn. Although these firstborn deserve to be slain by God, the firstborn of the children of Israel were redeemed by the Passover lamb. Because they were purchased, bought with a price, they did not belong to themselves. Thus, they had to separate themselves and become holy unto God.
By offering the firstborn unto God, the children of Israel remembered what God did at the time of the Passover. In our experience with the Lord we also should have this kind of remembrance. We should recall that, as firstborn in Adam, we should have been smitten by God, but instead we were redeemed by Christ, who became our substitute. Now we do not belong to ourselves; we belong to God. In 1 Corinthians 6:19 Paul says, “Do you not know that...you are not your own?” If we would live in Christ, we need always to remember that because Christ has redeemed us, we are not our own, but we belong to God. When we come to the meetings of the church, we may say to ourselves, “I was once in Adam, a fallen sinner. According to the righteous judgment of God, I should have been smitten. But I have been redeemed through Christ as my Passover lamb. Now I do not belong to myself. I belong to Him, and I must be separated unto Him.” We need to have this kind of remembrance day by day and even moment by moment.
Exodus 22:31 says, “And ye shall be holy men unto me.” According to the Bible as a whole, especially the New Testament, to be holy is to be saturated by Christ and with Him as our holiness before God. First Corinthians 1:30 says that Christ has been made unto us sanctification. For Christ to be our sanctification means that we are saturated with Him as holiness. In order to live in Christ, as God’s chosen people we need to have a holy life, a life saturated with Christ as holiness.