Not so sure thats the case; 'brood of vipers' etc...
When Jesus says that, He is judging them knowing them for whom they are. He is God. He can do that.
James 4:11 Speak not evil one of another, brethren. He that speaketh evil of his brother, and judgeth his brother, speaketh evil of the law, and judgeth the law: but if thou judge the law, thou art not a doer of the law, but a judge.
12 There is one lawgiver, who is able to save and to destroy: who art thou that judgest another?
That is not for us to judge fellow professing believers in that way. We can condemn the sin but not the saved believer. We can correct the believer, but hardly condemn him as if not a believer and thus not saved. Only God can judge that.
What we are to do by leaning on Him to help us in serving Him is this below...
2 Timothy 2:
24 And the servant of the Lord must not strive; but be gentle unto all men, apt to teach, patient, 25 In meekness instructing those that oppose themselves; if God peradventure will give them repentance to the acknowledging of the truth; 26 And that they may recover themselves out of the snare of the devil, who are taken captive by him at his will.
If you look at the next scriptural reference in how bad a brother can go astray....
2 Thessalonians 3:1 Finally, brethren, pray for us, that the word of the Lord may have free course, and be glorified, even as it is with you: 2 And that we may be delivered from unreasonable and wicked men: for all men have not faith. 3 But the Lord is faithful, who shall stablish you, and keep you from evil. 4 And we have confidence in the Lord touching you, that ye both do and will do the things which we command you. 5 And the Lord direct your hearts into the love of God, and into the patient waiting for Christ. 6 Now we command you, brethren, in the name of our Lord Jesus Christ, that ye withdraw yourselves from every brother that walketh disorderly, and not after the tradition which he received of us. 7 For yourselves know how ye ought to follow us: for we behaved not ourselves disorderly among you;............
14 And if any man obey not our word by this epistle, note that man, and have no company with him, that he may be ashamed. 15 Yet count him not as an enemy, but admonish him as a brother.
We can't really dismiss the wayward believer or even the former believer as if he or she is not a believer. And so when the moment that name calling and condemnation starts, whoever doing it does so not in the spirit of meekness and certainly not seeking any more to win back the lost, but has given in the flesh to bite and devour one another.
Galatians 5:14 For all the law is fulfilled in one word, even in this; Thou shalt love thy neighbour as thyself. 15 But if ye bite and devour one another, take heed that ye be not consumed one of another. 16 This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh.