The second thing we need to know about Angels is that they are spirit beings.
Hebrews 1:14, Which we cited above, is just one of a number of Bible references that tell us angels are Spirits. Satan and the demons are spirits too, and that’s why our spiritual battle is not “flesh and blood” (Ephesians 6:12). The angels are immaterial, invisible beings.
But even though this is true, angels can become visible to carry out specific,sovereignly directed supernatural activity on the earth. They did so on a number of occasions in scripture. One of the most familiar examples of this is Genesis 18, When Abraham welcomed three strangers to his tent. one of the visiters was the Lord Himself, and the other two were angels.
The Lord announced to Sarah that she was going to have a baby, The promised seed Issac. Abramham invited the three strangers to stay for a meal- and in the process of showing hospitality to them, he found the provision of God for the miracle he and sarah needed to produce a child at their greatly advanced ages.
The two angels who visited Abramham were also God’s provision for Abramham’s nephew Lot, for it was the angels who went on to Sodom in Genesis 19 to warn and rescue Lot from destruction.
Occasions like this are why the Bible says,
“DO NOT neglect to show hospitality to strangers, for by this some have entertained angels without knowing it”(Hebrews 13:2).
Sometimes when God wants to accomplish a specific work in a believer’s life, He will direct one of his invisible angels to become, visible to that believer, the belivever may not recognize that he is seeing an angel, since angels appear looking like men. The strangers the writer of Hebrews was talking about, were fellow believers who traveled about from place to place in that day and often needed lodging. The writer is saying that we should not refuse our hospitality to other believers, because God may be sending us the answer to our prayers. If we slam the door on people who need our help or hospitality, we may be slamming the door on God’s answer or his provision.