This question often arises when lines have been drawn and sides taken. Some may privately satisfy themselves that they are right by thinking: “The Lord is on MY side.”
You see, we are so egocentric that we question whether the Lord is on our side when the true question is this: “Am I on the Lord’s side?”
Before taking Jericho, Joshua met with the Lord. We know it was God because He accepted Joshua’s worship and told Joshua that the place he was standing was holy ground. God had previously told Moses the same thing at the burning bush (Exodus 3:5).
Before Joshua knew it was God in the flesh, he asked the man standing before him, “Are you my friend or enemy? Are you on my side or on the opposing side?”
God would have none of it. Listen to this brief conversation.
Joshua 5:13-15 (New Living Translation)
“When Joshua was near the town of Jericho, he looked up and saw a man standing in front of him with sword in hand. Joshua went up to him and demanded, ‘Are you friend or foe?’
‘Neither one,’ he replied. ‘I am the commander of the lord’s army.’
At this, Joshua fell with his face to the ground in reverence. ‘I am at your command,’ Joshua said. ‘What do you want your servant to do?’
The commander of the lord’s army replied, ‘Take off your sandals, for the place where you are standing is holy.’ And Joshua did as he was told.”

Rather than spend today wondering if God is on your side, spend your time making certain that you are on His side.