It is extremely dangerous to accept everyone as if they were from God because of deceit:
2 Cor 11:3-4 But I am afraid that just as Eve was deceived by the serpent’s cunning, your minds may somehow be led astray from your sincere and pure devotion to Christ. 4 For if someone comes to you and preaches a Jesus other than the Jesus we preached, or if you receive a different spirit from the Spirit you received, or a different gospel from the one you accepted, you put up with it easily enough.
2 Cor 11:13-15 For such men are false apostles, deceitful workmen, disguising themselves as apostles of Christ. And no wonder, for even Satan disguises himself as an angel of light. So it is no surprise if his servants, also, disguise themselves as servants of righteousness. Their end will correspond to their deeds.
It is foolish to accept any teaching from a spirit as the Holy Spirit before they are tested:
1 John 4:1 Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world.
Followers of other gospels disagreeing with the bible are cursed:
Galatians 1:6–9: I marvel that you are turning away so soon from Him who called you in the grace of Christ, to a different gospel, 7 which is not another; but there are some who trouble you and want to pervert the gospel of Christ. 8 But even if we, or an angel from heaven, preach any other gospel to you than what we have preached to you, let him be accursed. 9 As we have said before, so now I say again, if anyone preaches any other gospel to you than what you have received, let him be accursed.
One way to judge truth is by their actions:
1 John 2:9 ESV: Whoever says he is in the light and hates his brother is still in darkness.
Essential elements of wisdom from God include open to reason:
James 3:17 But the wisdom from above is first pure, then peaceable, gentle, open to reason, full of mercy and good fruits, impartial and sincere.
If you disagree with the teachings of Christ or even support those who do, you are wicked:
2 John 1:9-11: Everyone who goes on ahead and does not abide in the teaching of Christ, does not have God. Whoever abides in the teaching has both the Father and the Son. If anyone comes to you and does not bring this teaching, do not receive him into your house or give him any greeting, for whoever greets him takes part in his wicked works.
Practicing lawlessness leads to eternal destruction:
Matthew 7:21-23: “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’