The term separatism, or schism, denotes a denominational separation of religious groups from existing churches on nonScriptural grounds, such as ecclesiastical customs, forms, usages, and the like (Donatism). Schisms are therefore opposed to God's Word and are sinful. For practical reasons we distinguish between malicious separatism (schismatici malitiosi) and non-malicious separatism (schismatici non-malitiosi). The former is caused by, and mingled with, spite and uncharitableness; the latter is the result of ignorance or prejudice and is not joined with intentional disregard of the principle of brotherly love.
To apply the terms separatists and schismatics to persons who separate themselves from erring churches on account of their unsound doctrine or unscriptural practise is unjustified.
With regard to the right use of the doctrine of the Church, the Lutheran Catechism gives the following important directions. We use the doctrine of the Church properly, a) when we take heed to be and remain members of the invisible Church, 2 Cor. 13, 5; John 8, 31. 32; b) when we to this end adhere to the Church of the pure Word and confession and avoid all false churches, Matt. 7, 15; 1 John 4, 1; Rom. 16, 17; 2 Cor. 6, 14-18; and c) when we contribute toward its maintenance and propagation according to our ability, 1 Cor. 9, 14; Gal. 6, 6. 7; 1 Tim. 5, 17. 18; 1 Thess. 5, 12. 13; Mark 16, 15. 16; Matt. 28, 19. 20. These points deserve the constant consideration of every Christian believer and should be inculcated most diligently by the pastor in both his public and his private instruction.