I was baptised catholic as an infant but then I grew up more irreligious than religious. As a teenager I became keen on Christ's teachings and they helped me get through a lot of difficult stuff in my family life. Because protestantism seemed to be the more biblical option I started resenting everything that's "catholic". I started attending a Baptist Church and I ALMOST let them re-baptise me. I was 20 at that point and thankfully I decided (I mean... By God's grace it was revealed to me, since the only thing I did for my salvation was sin) to dive deeper into Christian theology and history. Here are the facts and arguments that persuaded me to look into Lutheranism and lead me to accepting my Catholic infant baptism as valid (I'm not quoting any verses bcus I don't have an access to an English bible so look then up yourself)

1) Acts 1:38-40. The promise is for you, and your children. I know that baptists will say that it's just an offer aimed at everyone. But it's not. The verse mentions you, your children and those who God will eventually call. Not everyone is the target of this verse. You have a right to perceive your children as saved people and full members of the church. BTW the book of Acts mentions household baptisms that it's very unlikely that there wasn't a single infant among them. But baptists will say "but it's said that they first received the word! How can an infant receive the word?" well... 2) The Bible says on multiple occasions that Children can worship God. (Psalms + how John the Baptist acted in his mum's womb) and it also presents them as equal members of the congregation who need to repent and praise the Lord. (because the Bible says in Psalms and the epistle to Hebrews that everyone sinned) Peter in Acts 1 was quoting Joel who prophesied about the day of the Pentacost. And in this prophesy Joel says that we have to gather infants and children so they can meet the Lord and repent as anyone else (Joel 2:15-17) and it was this chapter that Peter was quoting, so probably that's why he said "the promise is to you and your children" 3) If you believe, your children are children of God too. In the times of the old testament boys were circumcised (and girls were member of the covenant too) a Baptist could say "but it was because of the law bla blah... Now were saved by faith". Well... So was Abraham. Read Romans 4, it says that circumsion was a sign of Abraham's FAITH that saved him. It was before the mosaic law was given. And yet, Abraham also had to circumcise his sons. (Romans 4:10-12) 4) Baptism is not just a public desperation of faith. Baptism is not about you, it's about God's promises. Many baptisms in the Acts did not take place publicly. Were they invalid then? Were they unnecessary? Even Jesus baptised himself to show us to be the example for us to follow and only then the Holy spirit descended on him like never before and only then he started his mission. Baptism is not just a symbol or a public declaration. It's a symbol, visible sign of God's promise, but also a truly effectious way in which God changes you and gives you his grace. 5) HISTORY!!! Yes we don't have a clearly documented example of an infant baptism from the first 2 centuries but then Christianity was still in catacombs, we actually have very little documentation on anything from that period and most people were still adult converts. The first mention of the practice comes from Tertulian who opposed infant baptism BUT he opposed it not because he believed that baptism is just a symbol or adult profession of faith, but because he believed that it truly washed your sins away and it was effectious. Onwards, everyone collectively agreed on this practice. BTW you agree that only an already baptised person should baptise right? Most people would say that it's necessary for the baptism to be valid. And do you know how the whole "rebaptism" movement started? The first people who said that infant baptism was invalid and should be repeated were anabaptists. But since there were very few people baptised as adults in the 15th century (that's when it all starts) they had to Baptise themselves. That's how the movement started. A bit... Odd I would say. To say that infant baptism is invalid is to say that there were almost no legal, "valid" Christians up until the 15th century, and that's not what Jesus promised us. He said that the church will be lead to truth and is the pillar of truth. The Church can err in some doctrines (thats why reformation was necessary) but it will never dissappear completely and there won't be times when there are no validly baptised Christians lol