4 This issue arose because some false brothers had come in under false pretenses to spy on our freedom in Christ Jesus, in order to enslave us. -Galatians 2:4 BSB
The phrase “This issue” is about making believers go back to the Law of Moses to observe it and keep it. See verse 3 and its commentary.
What makes “some false brothers” is when they add to God’s Word, which changes it to say something other than what God said, and preaches it to others as the truth.
False teachers came to the Galatians and pretended to believe in sound teachings like salvation by grace through faith in Jesus Christ (Ephesians 2:8-9), not revealing to them that, in reality, they hold to work-based salvation. They teach that a person needs to keep the Law, which is works, plus believe in Jesus Christ to get saved. Read Galatians 3:1-2.
Paul understood that Satan is the one who influences false teachers, see 2 Corinthians 11:13-15, to enslave believers by entrapping them, teaching them to keep the Law, which makes them forsake the finished work of the cross, see Galatians 5:1-4. The cross—Jesus, who died for our sins (John 3:16, Romans 5:6-9), was to show us that our good works cannot atone for our sins and make us right in God’s eyes (Galatians 3:11). Only by accepting the gift that God offers through His Son, the Lord Jesus Christ, into our hearts by faith in Him can we have all of our sins forgiven.
2 I went in response to a revelation and set before them the gospel that I preach among the Gentiles. But I spoke privately to those recognized as leaders, for fear that I was running or had already run in vain. -Galatians 2:2 BSB
Paul received a revelation from the Holy Spirit, but he went to seek confirmation to make sure it was from the Holy Spirit (“…for fear that I was running or had already run in vain“), from those who walked with Jesus Christ while He was on earth, see verse 9.
Paul shared with the spiritual leaders of the faith the gospel that he was presenting to the Jews and Gentiles. He wanted to know that the gospel he was preaching was that of Jesus Christ, as he was getting a lot of opposition from false believers. Paul made himself accountable to the Apostles.
27 As Jesus went on from there, two blind men followed Him, crying out, “Have mercy on us, Son of David!” 28 After Jesus had entered the house, the blind men came to Him. “Do you believe that I am able to do this?” He asked. “Yes, Lord,” they answered. 29 Then He touched their eyes and said, “According to your faith will it be done to you.” -Matthew 9:27-29 BSB
A Christian’s faith is not the source of healing. Jesus is the source. Jesus only responds when we exercise our faith in believing that He can do what we ask of Him if it’s according to His will (1 John 5:14).
In James 1:5-7, it says that if you ask God for wisdom but you doubt that He will give it to you, then do not expect to receive it. God will only act on your prayer when you believe that He can and will do it, giving you spiritual wisdom and knowledge.
6 And without faith it is impossible to please God, because anyone who approaches Him must believe that He exists and that He rewards those who earnestly seek Him. -Hebrews 11:6 BSB
A faithless person cannot expect to please God or even think that they will have their prayer answered. To some extent, this applies to a genuine believer in Jesus Christ. If we go to Jesus with doubt when we pray, don’t expect an answer from the Lord. But, if we are honest with the Lord and say to Him, as we see in Mark 9:24, which says, “Immediately the boy’s father cried out, “I do believe; help my unbelief!” That type of honesty Jesus answers because He knows our weaknesses and inadequacies. The boy’s father came to Jesus, saying to Him that he was struggling with faith. He had faith mixed with doubt. Even though the Scriptures didn’t say what happened to his weak faith after Jesus helped his son, we can logically conclude that his doubts went away when Jesus healed his son.
Seeking the Lord through prayer and reading God’s Word is how one’s faith gets stronger and doubt is pushed out.