On Sunday morning, Rev. Kenneth I. MacLeod preached on Genesis 18:17, 'God's appointments are always on time'.

Abraham was at the centre of God's plans and appointments in the world, as can be seen from the chosen passage. However, it is important to remember that the church of Christ is also at the centre of His plans - God's people are His portion in the world, and are all He will take out of it at the end.

At the opening of this chapter, Abraham is enjoying a rest, when he is suddenly surrounded by three men. These are actually two angels and the Son of God in the guise of ordinary men. Although we cannot know what an angel's habitual appearance would be like, we do know that they are ministering spirits, watching over God's people.

It isn't certain who Abraham initially thought his visitors were, but he welcomed them with traditional Near Eastern hospitality. This was culturally ingrained, as well as being viewed as a sacred duty. There is an example in this for us, as we see Abraham's alacrity in ministering to the Lord - there is no hesitation whatsoever.

In addition to his readiness to serve, Abraham here demonstrates other elements of good spiritual conduct. He gave generously, selecting the best for the Lord; and he also showed a combination of boldness and humility which was very acceptable to God.

It is not obvious when Abraham realised that these were Heavenly visitors. The truth did dawn on him, however, and - if not before - certainly when the Lord asked for Sarah. His use of her new, God-given name was enough of a clue to His own identity.

This is where the promise regarding a covenant child for Sarah and Abraham is reaffirmed in quite specific terms. God has kept them waiting until their time of natural childbearing is long past. This fact will underline that the ensuing provision is all of Him. In that respect, we might call Isaac's a supernatural birth.

When Sarah overheard what the Lord said, she laughed - not mirthfully, but disbelievingly. Even although she was in the tent and laughing more to herself than to be heard, the Lord knew and asked why she had laughed. Though she denied it, nonetheless He knew. This is a wonderful illustration of God's access to the innermost secrets of our hearts.

In verse 14, the Lord reiterates that he WILL return, underlining that nothing is impossible with Him. He rules over all, and has a purpose in everything.

As they progress towards Sodom, Abraham is left alone with the Lord, locked in prayer. Time alone with Him is crucial, as we know from Matthew 6:6. Aside from demonstrating the value of solitude with God, the passage also highlights the importance of perseverance. When the human heart has grown cold towards God, it may take a little time to thaw.

In Abraham's prayer it is evident that more time spent in closeness with the Lord leads to greater humility and greater boldness in approaching him. He begins by reducing the number of potentially righteous people by fives, and then by tens. Yet, accompanying this boldness is his awareness of his own insignificance- 'I who am but dust and ashes' - besides the greatness of God.

God's willingness to save is very apparent here. As we know from 2 Peter 3:9, He is not willing that any should perish. If we live in closeness to Him, as Abraham did, He will reveal more of Himself to us.