We see St Paul writing to Galatians at Gal 1: 6-8 (NRSVCE):
I am astonished that you are so quickly deserting the one who called you in the grace of Christ and are turning to a different gospel— not that there is another gospel, but there are some who are confusing you and want to pervert the gospel of Christ. But even if we or an angel from heaven should proclaim to you a gospel contrary to what we proclaimed to you, let that one be accursed!
KJV has a slightly different translation of Gal 1:8:
But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.
One wonders as to why Paul invokes the imagery of an angel proclaiming a different Gospel at the risk of getting condemned for the act, to tell the Galatians that the Gospel he preached was authentic. Does he indirectly mean that angels have free will and can deviate from their entrusted mission while on earth? My question therefore is: Can angels deviate from their entrusted mission while on earth?