Secondary doctrines are those that are important, but are not essential to salvation. One can be wrong on secondary doctrines and still be saved. Although Christians agree on essential doctrines, they may disagree with each other on secondary doctrines. These include:
- Infant baptism vs Believer's baptism
- Calvinism vs Arminianism etc.
- Premillennialism vs Amillennialism vs Postmillennialism
- Cessassionalism vs Continualism
- Complementarianism vs Egalitarianism
- Young Earth Creationism vs Old Earth Creationism etc.
Problem arises when we consciously or unconsciously promote a secondary doctrine to the same level of importance as a primary doctrine. When we debate with brothers and sisters who disagree with us, we are tempted to demonize them by assigning impure motives to them in our hearts, even if we don't doubt their salvation. Yet as Christians, we ought to be charitable and realize that these brothers and sisters are loved by God just as we are. They have the Holy Spirit just like we do. God has shown mercy to them just as He has shown mercy to us. They will be in heaven just as we will, and on that day, there will be no more disagreement between us and them.
Moreover, we should be careful when speaking against theologians who have fallen asleep and have gone on before us, even though they may strongly disagree with us on secondary doctrine. They are currently in heaven, and those who disagreed with each other on doctrine in the past are now in full agreement in heaven. By now, people like Luther, Calvin, Arminus, Whitfield, Wesley all have the same soteriology, ecclesiology, pneumatology, and eschatology. There are no prolonged doctrinal debates in heaven. How can there possibly be? A dialogue between two Christians in heaven might be as follows:
Christian A: Your theology of salvation was so messed up.
Christian B: Guess what? You're right! But Jesus in His grace saved me anyways.
Christian A: See, I told you so back then. How could you have been so wrong?
Christian B: I don't know. But I know that God is merciful, and He loves me. Praise God!
Christian A: Praise God!
So while we study Scripture, we may have in-house debates with each other on secondary doctrine, but we do so charitably, realizing we do not know everything there is to know about God, even though we know Him and are known by Him.
May our lives be pleasing to God as we continue to study the Bible and walk with Him!