I confess, at first I thought this was ridiculous question. But after thinking about it. It is a good and valid question.
So I will answer this question with a question.
1 Pet 5:8; Be of sober spirit, be on the alert. Your adversary, the devil, prowls around like a roaring lion, seeking someone to devour.
1 Pet 5:9; But resist him, firm in your faith, knowing that the same experiences of suffering are being accomplished by your brethren who are in the world.
Jas 4:7. Submit therefore to God. Resist the devil and he will flee from you.
We are obviously told to "resist" the devil.
I agree with @Wired4Fishen above about Ephesians
Eph 6:16; in addition to all, taking up the shield of faith with which you will be able to extinguish all the flaming arrows of the evil one.
We are able to extinguish these flaming arrows (or darts as some Bible say) that come from.... the evil one (Satan)
So how do we resist Satan? Do we arm wrestle him? Have you ever had physical arrows or darts shot at you?
What exactly are we resisting, when we are resisting Satan?
Could it be...
2 Cor 10:5; We are destroying speculations and every lofty thing raised up against the knowledge of God, and we are taking every thought captive to the obedience of Christ,
and Wired4 mentioned above in Ephesians 6 it says...
Eph 6:12; For our struggle is not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness, against the spiritual forces of wickedness in the heavenly places.
If we aren't fighting physical things, what are we fighting? What are we resisting?
Also
@Dave M
To add to what has been said.
Where do those thoughts of doubt come from?
We need to know and Believe God's Word to the point we can quickly recognise any attempt our enemy is coming at us with.
he is as an expert craftsman at hand tailored and camouflaged thoughts for each individual. he knows you better then you think. he has studied your reactions, your emotions and can read your body language unto the point he knows when you are biting his deception.
his deception is not easily recognised.
he will mix in truth and use scripture with a false meaning. Even just the slightest little twist that goes unnoticed and begins to hinder your thinking.
Another thing.
Have you ever struggled in an area that was hard for you to resist?
Ever wrestle with thoughts on how it is not that bad or been pushed to just do it?
Then after words felt like crap and had thoughts of how disgusting you were and how your not a Christian or God is mad now and so forth?
The same one who pushed you into it is the first one condemning you and yes it is your enemy the devil, or more likely the demon(s) that is assigned unto you at the time.
People who think they are so perfected that the devil can not influence them are Already Half Beat.
No one is to the place where satan will not address thoughts to.
Just also know that these fiery darts, thoughts can and will come with FEELINGS and emotions.
One other example, ever get angry and start mouthing off in an argument and once you got started it was hard to Stop and you said things that you could not believe you were saying?
Like a stuck horn or rapid fire machine gun?
That was your enemy feeding you those thoughts and your flesh had taken over and spit them out just as fast as he could put them in you.
How does satan get the open door he is looking for?
Words. .. your words....he has to have our help. We must give him the legal right. Words and actions and reactions are vital.
Where do all those thoughts come from that gets a person to judge another?
Yep your enemy.
Why ? To get judgement on you.
he knows when we judge others, he has a legal right to begin to devour.
Where do all these arguments come from about Judging with Christians?
Why so many beliefs or so called doctrines about we are to Judge People and claim this false teacher and so on?
Church Splits stem from some one acting on a thought. Does God go around breaking up churches and starting new ones with different beliefs then what He has said in His Word?
Our thoughts are influenced even if you don't believe it.
Add in.....how do you give life to a thought - SPEAKING IT and or acting on it.
Blessings to you