Biblical counseling relies on principles that God has provided in His Word, on the Holy Spirit, and on the power of prayer. God says that the "natural man" (unsaved) cannot know the things of God because spiritual truth must be spiritually discerned (1 Cor. 2:14).
Psychology and Psychiatry represent the voice of ungodly man, and the Bible is the voice of God. Psychology is rooted in human wisdom, the teachings of the Bible are God's wisdom.
(Jeremiah 17:5-9 )  This is what the LORD says: "Cursed is the one who trusts in man, who depends on flesh for his strength and whose heart turns away from the LORD.  He will be like a bush in the wastelands; he will not see prosperity when it comes. He will dwell in the parched places of the desert, in a salt land where no one lives.  "But blessed is the man who trusts in the LORD, whose confidence is in him.  He will be like a tree planted by the water that sends out its roots by the stream. It does not fear when heat comes; its leaves are always green. It has no worries in a year of drought and never fails to bear fruit."  The heart is deceitful above all things and beyond cure. Who can understand it?
(2 Timothy 3:1-5 )  But mark this: There will be terrible times in the last days.  People will be lovers of themselves, lovers of money, boastful, proud, abusive, disobedient to their parents, ungrateful, unholy,  without love, unforgiving, slanderous, without self-control, brutal, not lovers of the good,  treacherous, rash, conceited, lovers of pleasure rather than lovers of God- having a form of godliness but denying its power. Have nothing to do with them.
(Romans 6:16-18 )  Don't you know that when you offer yourselves to someone to obey him as slaves, you are slaves to the one whom you obey-whether you are slaves to sin, which leads to death, or to obedience, which leads to righteousness?  But thanks be to God that, though you used to be slaves to sin, you wholeheartedly obeyed the form of teaching to which you were entrusted.  You have been set free from sin and have become slaves to righteousness.
(Matthew 11:28-30 NIV)  "Come to me, all you who are weary and burdened, and I will give you rest.  Take my yoke upon you and learn from me, for I am gentle and humble in heart, and you will find rest for your souls.  For my yoke is easy and my burden is light."
The Christian counselor is responsible to tell the counselee the Truth, that their complete salvation is in the person of Jesus Christ, not in some substitute offered by psychology. When dealing with unsaved people or immature Christians, this may take some time to present and may meet with rejection. Pray for those who cannot accept Biblical counseling and release them, entrusting them to God to send other laborers to till the soil and water the seeds you have planted. Never be tempted to compromise life-giving truth by substituting godless therapy for the sake of "helping" somehow. Do not be yoked together with unbelievers. For what do righteousness and wickedness have in common? Or what fellowship can light have with darkness? What harmony is there between Christ and Belial? What does a believer have in common with an unbeliever? What agreement is there between the temple of God and idols? For we are the temple of the living God. As God has said: "I will live with them and walk among them, and I will be their God, and they will be my people. Therefore come out from them and be separate, says the Lord. Touch no unclean thing, and I will receive you. I will be a Father to you, and you will be my sons and daughters, says the Lord Almighty." Since we have these promises, dear friends, let us purify ourselves from everything that contaminates body and spirit, perfecting holiness out of reverence for God. (2 Corinthians 6:14-18 & 7:1)
But I fear, lest by any means, as the serpent beguiled Eve through his subtlety, so your minds should be corrupted from the simplicity that is in Christ. (2 Corinthians 11:3 )
See to it that no one takes you captive through hollow and deceptive philosophy, which depends on human tradition and the basic principles of this world rather than on Christ. (Colossians 2:8 )
Blessed is the man who walks not in the counsel of the ungodly, nor stands in the path of sinners, nor sits in the seat of the scornful; but his delight is in the law of the Lord, and in His law he meditates day and night. He shall be like a tree planted by the rivers of water, that brings forth its fruit in its season, whose leaf also shall not wither, and whatever he does shall prosper. (Psalms 1:1-3 )
Timothy, guard what has been entrusted to your care. Turn away from godless chatter and opposing ideas of which is falsely called knowledge, which some have professed and in so doing have wandered from the faith. (1 Timothy 6:20,21 )
People will be lovers of themselves, lovers of money, boastful, proud, abusive, disobedient to their parents, ungrateful, unholy, without love, unforgiving, slanderous, without self-control, brutal, not lovers of the good, treacherous, rash, conceited, lovers of pleasure rather than lovers of God--having a form of godliness but denying its power. Have nothing to do with them. They are the kind who worm their way into homes and gain control over weak-willed women, who are loaded down with sins and swayed by all kinds of evil desires, always learning but never able to acknowledge the truth. (2 Timothy 3:1-7)
For no one can lay any foundation other than the one already laid, which is Jesus Christ. (1 Corinthians 2:11