The word of God is the truth. Anyone who tells this truth is doing God's will. Either this message is passed during a sermon or debate does not matter. As long as people get to hear the gospel of Christ, and God is glorified in all. We must however be careful and wise, that our debates do not generate arguments, which can in turn, be aggravated into enmity.
2 Timothy 2:23 But foolish and unlearned questions avoid, knowing that they do gender strifes.
24 And the servant of the Lord must not strive; but be gentle unto all men, apt to teach, patient,