how does one know they are being led by the Holy Spirit as opposed to their own spirit?
for example, Lutherans and Baptists both proclaim belief in sola scriptura, both use the same 66 book Bible.
Lutherans believe in infant baptism and look to the Scriptures for support and believe the Holy Spirit leads them to this belief.
Baptists reject infant baptism and look to the Scriptures for support and believe the Holy Spirit leads them to this belief.
now, which one is led by the Holy Spirit as it relates to infant baptism and which is being led by their own spirit?
Three times in or it doesn’t count. By the Dunkard standard none of these folks are Christians!
I wasn't sure if this was a serious question, but here you go.
The man who enters by the gate is the shepherd of his sheep. The watchman opens the gate for him, and the sheep listen to his voice. He calls his own sheep by name and leads them out. When he has brought out all his own, he goes on ahead of them, and his sheep follow him because they know his voice.
read all of John 10 - It is quite comforting to Believers.
You, dear children, are from God and have overcome them, because the one who is in you is greater than the one who is in the world. They are from the world and therefore speak from the viewpoint of the world, and the world listens to them. We are from God, and whoever knows God listens to us; but whoever is not from God does not listen to us. This is how we recognize the Spirit of truth and the spirit of falsehood. 1 John 4:4-6
If you are Born Again, you have received a new heart (spirit). Its your mind that needs renewal to the Word of God. That is where the battle will be until the spirit takes its proper role in charge.
We are to be led by our recreated spirit which is the home of the Holy Spirit. If you spend all your time listening to traditions of men, social gospel or the world, and no time with God and His Word, you will have lots of trouble and get easily led astray by the evil one because you will not recognize the Good Shepherd's voice. The Holy Spirit will never contradict the Word. This is an additional check that the Believer can use who has studied and fed on the Word continually. (See John 14 & 16, Romans 8 & 12, Colossians 3 and Ephesians 4)
“now, which one is led by the Holy Spirit as it relates to infant baptism and which is being led by their own spirit?”
That is for G-d to determine. He can also decide if He wants to condemn either of them for their method of baptism.