One Baptism

Ephesians 4:1-6

As a prisoner for the Lord, then, I urge you to live a life worthy of the calling you have received. Be completely humble and gentle; be patient, bearing with one another in love. Make every effort to keep the unity of the Spirit through the bond of peace. There is one body and one Spirit, just as you were called to one hope when you were called; one Lord, one faith, one baptism; one God and Father of all, who is over all and through all and in all.

Matt looked at 3 different occasions where ‘Baptism’ is used in the NT.

John the Baptist’s baptism, which was for Repentance in preparation for the messiah to come, Christ.
Baptism in the Holy spirit, but Paul usually adds ‘in the spirit ‘afterwards so as not to confuse it with water baptism.
Water baptism something all believers went through as a public declaration of their commitment to Christ. What is important to grasp in this ‘One Baptism’ scripture is that it is something Christ initiated for all his followers, as a sign of their being ‘immersed’ into Him. Something the poorest of the poor can do; something the simplest person can do, you don’t even have to be able to read. It is for all and can be carried out by all. (Matt 28)

In this instance (Eph 4:5), Paul is clearly talking about water baptism. Andrew Lincoln comments on this verse: “This baptism is one, not because it has a single form, or is administered only on one occasion, but because it is the initiation into Christ, into the one body, which all have undergone and as such is a unifying factor".

At times believers had known Christ and his salvation in their lives, but had not yet been baptised in water because they were ignorant of the importance of it.

Acts 18 tells us about Apollos who had “a thorough knowledge of scripture” and had been “instructed in the way of the Lord” however it also points out that he knew only John’s baptism. Matt told his own story of being a Christian for some years before he was baptised, because he hadn’t heard this teaching previously.

Questions:

Paul is making the case in Eph. 4 that there should be unity in the church because there is one Lord, one faith, and one baptism. Why is it so important that all Christians are baptised in water following their conversion?
Some people were baptised immediately after they had made a profession of faith, like the Ethiopian eunuch in Acts 8; whereas others like Apollos in Acts 18 hadn’t heard about this water baptism until much later. Why can it be more difficult to ask to be baptised some time after you have made a profession of faith?
If we don’t need to be baptised in water to be saved (faith alone); why do we do it?
Matt told the story of Naaman in 2 Kings 5 who was cleansed of his leprosy because he obeyed Elisha and immersed himself in the Jordan 7 times. This was quite a humbling experience for him, why? How can we be like Naaman when it comes to baptism?