Since we have mental illness before therapy, it would be stupid to do nothing with it and just let it eat you up mentally. How did people (specifically Christians) dealt with mental issues before the modern therapy?
There have always been counterfeits of God's way to a serene, stable and joyful inner life. But not being of God, they always diverge from Him, making the system or process of obtaining inner peace, and the feeling of peace itself, more important than He is. God made us all, though, to find the truest inner peace, the deepest joy, the greatest fulfillment and the highest meaning in Himself. All who live according to the purposes for which they were made, that is, according to God's will and way, have no need of psychotherapy. God is far more than enough.
So, then, the one who knows God (
Philippians 3:7-14), who believes Him (
Hebrews 11:6), who loves (
Matthew 22:36-38) and submits to Him (
Romans 12:1; Romans 6:13-18; James 4:7), is the one who most enjoys Him. Such a person is filled with who God is, with His love, joy, peace, gentleness, goodness, patience, etc. (
Galatians 5:22-23), and is thus the stablest, wisest, holiest, and most fulfilled of people. And, this person is also the only kind of person who is truly worshipping God, who is properly glorifying Him, and thus fulfilling the ultimate reason for their existence (
1 Corinthians 10:31).
Sadly, such a person is increasingly rare in our ever-darkening world. The Church in North America is, instead, crowded with Self-lovers, people who have made God their mirror, not their Master, and are thus filled with all the neuroses, psychological pathologies and sin that being their own god, worshipping their own image reflected in the mirror they've made of God, always produces.