‘And passing along by the Sea of Galilee he saw Simon, and Andrew, Simon's brother, casting a net in the sea, for they were fishermen. And Jesus said to them, “Come after me, and I will make you to become fishers of men.” And immediately they left the nets and followed him.'
Luke describes the whole incident in great detail (Mark 5:1-11) but here in Mark we have the bare bones. Mark is concerned to express the stark demand, and the response to the Kingly Rule of God. ‘Passing along by the Sea of Galilee.' It was more strictly a Lake (so Luke) but the use of ‘Sea' is typically Semitic.
‘He saw Simon and Andrew, Simon's brother casting a net in the sea.' This condenses all that happened in a single phrase, but its mention is necessary to illuminate the phrase that follows later about ‘fishers of men'. It was because they were fishermen that Jesus told them that they would become fishers of men. He suited His illustrations to the understanding of His hearers.
‘Come after me, and I will make you to become fishers of men.' The call was absolute. They were to follow Him and to be no longer fishermen, but fishers of men. Note how the call comes even while they are fishing. Their abandonment of their occupation is a requirement for following Him. Interestingly the illustration of fishing men is used elsewhere in the sense of fishing men for judgment (Jeremiah 16:16), but it is in itself neutral. And besides when God's judgment goes forth the people learn righteousness. The idea was that from now on they would use their abilities and skills to win men under the kingship of God. Andrew had already shown himself adept at that (John 1:41). And now Jesus was making clear that He had a wide ministry for them in view.
‘They left the nets and followed Him.' The comment that they left their nets is to stress that they left instantly and that it was permanent. The nets were left just where they were, although no doubt looked after by the family. They were no longer needed. We may not be called on to leave our nets, but we are to use them for God's purposes. ‘Followed Him.' The idea of following in this sense involves trust, commitment and obedience.