I know that Jesus is omnipresent and omnipotent, but why does He have to use angels to guard His children on earth? Why use them if He can do it by Himself? Can we talk to angels?
You are certainly right in saying “Jesus is omnipresent and omnipotent,” for Jesus is God! Jesus spoke of His omnipresence to His disciples in Matthew 28:20, “Lo, I AM WITH YOU ALWAYS, even to the end of the age” (NKJV). His omnipotence is brought before us in Hebrews 1:3 where it is said that He is “upholding all things by the word of His power.” Because He is everywhere and all-powerful, He really doesn’t need to use angels in service to mankind, but He is also SOVEREIGN and in His sovereignty He chose to create angels to serve His purposes and one of those purposes is to serve believers here on earth. Hebrews 1:14 speaks to this: “Are they (angels) not all ministering spirits sent forth to minister for those who will inherit salvation.”
Your question may be taken to mean that each believer has a “guardian angel,” but does Scripture support that view? We just saw from Hebrews 1:14 that angels definitely serve believers but does God actually assign a certain angel to a certain individual? One passage that has been used to support this view is Psalm 91:9-12, “Because you have made the LORD, who is my refuge, even the Most High, your dwelling place, no evil shall befall you, nor shall any plague come near your dwelling; for He shall GIVE HIS ANGELS CHARGE OVER YOU, TO KEEP YOU IN ALL YOUR WAYS. In their hands they shall bear you up, lest you dash your foot against a stone.” This passage clearly teaches us that God has commissioned angels to protect believers during difficult times, but it would be hard to conclude that each believer has his/her own “guardian angel.”
Another scripture which SEEMS to suggest that each believer has a guardian angel is Matthew 18:10, “Take heed that you do not despise one of these little ones, for I say to you that in heaven THEIR ANGELS always see the face of My Father who is in heaven.” Some who espouse this view say that “these little ones” are referring to “believers.” Others, who also teach there are guardian angels, believe “these little ones” refer to actual “little children” and thus in their view every “little child” has their own personal angel in heaven who is watching over them. There is also a THIRD VIEW, for some believe the word “angel” here refers to the “departed spirit” of a child who has died. In this case there is no thought whatsoever of a personal guardian angel. Because of the divergent views (by godly expositors), it is best not to be dogmatic.
What we do know for certain, is that angels do indeed serve believers in many ways, especially in protecting them from physical harm. One well-known example is found in Acts 12:1-10 where an angel helped Peter escape from prison and certain death. After the angel’s intervention Peter said, “Now I know for certain that the Lord has sent His angel, and has delivered me from the hand of Herod and from all the expectation of the Jewish people” (verse 11). See also Daniel 6:16-22 and Acts 5:17-20 for other examples of angels protecting believers from physical danger.
In closing, you had asked, “Can we talk to angels?” There are instances in the Bible where angels appeared to men and they had conversations together (see Genesis 18:1-9 and 19:1-3 along with Hebrews 13:2), so it is possible. Yet we never told to “pray to angels.” We are to pray directly to God the Father in Jesus Name (see John 14:12-13; 15:7, 16:23-24, 26). To pray to an angel would be tantamount to worshipping angels instead of God. The Word of God condemns that and angels themselves forbid it, as we see in Revelation 22:8-9, “I John…fell down to worship…the angel…he said to me, ‘See that you do not do that. For I am your fellow servant….Worship God.’” (401.3) (DO)